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Ghostbusters Cupcakes

It’s finally spooky season and that means watching all my favorite Halloween movies!! For me, Hocus Pocus and Ghostbusters are absolute musts. After watching Ghostbusters this past weekend, I was inspired to make these slimer-inspired Ghostbusters cupcakes.

They’re made with fluffy lime cupcakes, a lime “ectoplasm” curd and are topped with a lime buttercream frosting.

I used a bit of fondant to get Slimer’s face just right, but you could also use frosting if you prefer!

image of slimer ghostbuster cupcakes made with lime cupcakes

The Perfect Ectoplasm Filling for These Ghostbusters Cupcakes

While I love baking cute things, I wanted these Slimer cupcakes to have a somewhat spooky vibe…or as spooky as possible with a silly fondant face!

I envisioned these cupcakes with an ectoplasm-esque filling and the first thing that popped into my head was lime curd. Ironically lime curd is not naturally green, but it’s the perfect gooey consistency.

With the help of some green gel food coloring, the filling in these cupcakes looks a scene right out of Ghostbusters. It also is delicious and really packs these cupcakes with lime flavor.

Substitutions and Swaps

While I love this recipe just the way it is, I know some of you might not have all of these ingredients on hand!

Below are some swaps and substitutions that can be made in this recipe:

  • Unsalted Butter – If you only have salted butter on hand, you can use it in place of the unsalted butter in this recipe. Just be sure to omit the salt that this frosting recipe calls for. You can also use vegan butter in its place!
  • Granulated Sugar – I do not recommend reducing the amount of sugar or changing the type of sugar, as it will change the texture of the cupcakes.
  • Egg Whites – You can use 2 whole eggs in place of the 3 egg whites in this recipe, or you can use egg whites from a carton.
  • Sour Cream – Use full fat yogurt, buttermilk, whole milk, or an alternative yogurt or milk (almond, soy, oat, etc.) if you’re dairy free.
  • Whole Milk – You can also use full fat yogurt, buttermilk, sour cream, or an alternative yogurt or milk (almond, soy, oat, etc.) if you’re dairy free.
  • Fresh Lime Juice & Zest – In a pinch you could use lemon juice and zest, but I don’t recommend using bottled lemon juice! The flavor just isn’t as strong.
  • Vanilla extract – If you don’t have any on hand you can use lime or lemon extract in its place.
  • All Purpose Flour – This recipe turns out best with AP flour, but you can use a gluten free flour blend or cake flour if that’s all you have on hand.
image of ghostbuster cupcakes decorated to look like slimer

Tips for Making the Best Ghostbusters Cupcakes

  • Use a cookie scoop to easily fill your cupcake liners and make sure they all have the same amount of batter.
  • Ingredients at room temp mix together better! Set cold ingredients ahead of time.
  • Bang your cupcake pan on the counter before putting it in the oven. This brings any air bubbles that are trapped in the batter to the surface.
  • To give these cupcakes some serious Ghostbusters vibes, fill them with lime curd to look like ectoplasm!
  • Use a large, round piping tip to frost your cupcakes! I used an Ateco 805.

Making These Ghostbusters Cupcakes in Advance & Storage Tips

You can make these Ghostbusters cupcakes in advance. If stored unfrosted and unfilled in an airtight container, they can last for 2 days at room temperature or up to a week in the fridge.

These cupcakes can also last up to 3 months in the freezer. If you plan to freeze them, wait to fill and frost them until they’re thawed.

image of green buttercream frosting

You can also make your frosting and filling up to a week ahead of time or save any leftovers. Leftover lime curd can be stored in an airtight container in the fridge for up to a week and leftover frosting will last in the fridge for up to a month.

Be sure to give the frosting a good stir once it thaws to get the consistency nice and smooth again.

Frosted cupcakes shouldn’t sit out at room temperature for more than a day because the lime curd can spoil. Store them in the fridge in an airtight container once they’re frosted.

image of slimer cupcakes on counter

Let Me Know What You Think!

If you try making these Ghostbusters cupcakes, I’d love to hear what you think of them! Please leave a rating and comment below.

Tag me @chelsweets and use #chelsweets so that I can see your amazing creations on social media!

image of ghostbuster cupcakes filled with lime curd to look like ectoplasm

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Yield: 12 cupcakes

Slimer Ghostbusters Cupcakes

image of slimer ghostbuster cupcakes made with lime cupcakes

These Ghostbusters-inspired Slimer cupcakes are made w/ fluffy lime cupcakes & lime curd slime filling. They're equally spooky & delicious!

Prep Time 30 minutes
Cook Time 15 minutes
Additional Time 30 minutes
Total Time 1 hour 15 minutes


Lime Slimer Cupcakes

  • 6 Tbsp (3/4 of a stick) unsalted butter, room temperature (85g)
  • 3/4 cup granulated sugar (150g)
  • 1/3 cup pasteurized egg whites or 3 egg whites (90g)
  • 1/3 cup sour cream (80g)
  • 1/3 cup whole milk (80g)
  • 1/4 cup lime juice (60g)
  • 1 tsp vanilla extract (4g)
  • 2 tsp lime zest (4g)
  • green gel food coloring
  • 1 1/4 cups all-purpose flour (165g)
  • 2 tsp baking powder (8g)
  • 1/4 tsp fine salt (2g)

Lime Curd

  • 3 large eggs (168g)
  • 3/4 cup granulated sugar (150g)
  • 1/4 tsp fine salt (2g)
  • 1/2 cup fresh lime juice (120g)
  • 1 Tbsp lime zest (6g)
  • 6 Tbsp (3/4 stick) unsalted butter (85g)
  • electric green gel food coloring

Lime Buttercream Frosting:

  • 1 cup unsalted butter, room temp (226g)
  • 2 Tbsp lime juice (12g)
  • 1 tsp lime zest (2 grams)
  • 1 tsp vanilla extract (4g)
  • 1/2 tsp fine salt (3g)
  • 3 1/2 cups powdered sugar (438g)
  • electric green gel food coloring

Cupcake Decorations

  • 1/4 cup red fondant
  • 1/4 cup black fondant
  • 1 Tbsp yellow fondant
  • 1 Tbsp white fondant


Lime Slimer Cupcakes (adapted from The Cake Blog)

  1. Preheat the oven to 350°F / 175°C and line a cupcake pan. Set aside.
  2. In a large bowl or the bowl of a stand mixer, cream together 6 Tbsp butter and 3/4 cup sugar until the mixture becomes lighter in color (1-2 minutes).
  3. Mix in 3 egg whites on a medium speed, scraping down the sides and bottom of the bowl as needed with a rubber spatula.
  4. Mix in 1/3 cup sour cream, 1/3 cup whole milk, 1/4 cup lime juice, 1 tsp vanilla, 2 tsp lime zest and a squirt of gel food coloring on a medium speed until combined.
  5. In a separate bowl, whisk together 1 1/4 cups flour, 2 tsp baking powder and 1/4 tsp salt.
  6. Mix in the dry ingredients in two additions, mixing on a low speed until just combined. Be careful not to over-mix the batter!
  7. Fill the cupcake liners 3/4 full and bake for 15-17 minutes or until a toothpick comes out with a few moist crumbs.
  8. Remove cupcakes from oven and let them to cool for 2-3 minutes in the pan, then place them on a wire rack to finish cooling.

Lime Curd "Slime" Filling

  1. While the cupcakes bake and cool, make the lime curd filling.
  2. Whisk together 3 large eggs, 3/4 cup sugar, 1/4 tsp salt, 1/2 cup lime juice and 1 Tbsp lime zest in a medium saucepan until smooth.
  3. Heat over a medium low head for 10-15 minutes stirring constantly until the mixture thickens.
  4. Turn off the heat and stir in 6 Tbsp of butter and a squirt of electric green gel food coloring until smooth and evenly colored.
  5. Pour into a separate bowl to cool and set aside.

Lime Buttercream

  1. As the lime curd filling cools, make the lime buttercream.
  2. Beat 1 cup of room-temperature butter on a medium-high speed for 2 minutes with a whisk attachment until the butter becomes lighter in color.
  3. Mix in 2 Tbsp lime juice, 1 tsp lime zest, 1 tsp vanilla extract, 1/2 tsp salt, and a generous squirt of electric green food coloring on a low speed.
  4. Slowly mix in 3 1/2 cups of powdered sugar, 1 cup at a time on a low speed.
  5. Mix on low for a couple minutes until the ingredients are fully incorporated and the desired consistency is reached. 
  6. If the frosting is too thick, add in additional lime juice (1 Tablespoon at a time). If the frosting is too thin, add in more powdered sugar (1/4 cup at a time).

Assembling These Slimer Cupcakes

  1. Use a small knife or 1 inch circle cutter to remove the center from each cooled cupcake.
  2. Fill each cupcake with a generous spoonful of lime curd.
  3. Pipe a large swirl of lime buttercream on top of each cupcake using a large round piping tip. Chill the cupcakes in the fridge for 10 minutes or the freezer for 5 minutes to help the frosting firm up.
  4. While the cupcakes chill use black, white, yellow, and red fondant to make Slimer's mouth and eyes.
  5. Remove the cupcakes from the fridge and add a Slimer face to each cupcake, then enjoy!


This recipe can also be used to make mini Slimer cupcakes! It makes about 40 mini cupcakes, which only need to bake for 8-10 minutes.

Make these Ghostbusters Slimer cupcakes in advance!! If stored unfrosted in an airtight container, they can last for:

  • 1 day at room temperature
  • Up to a week in the fridge
  • Up to 3 months in the freezer

Make your frosting ahead of time too or save any leftover frosting! It can be stored in an airtight container in the fridge for up to a month, or in the freezer for up to 3 months. Be sure to give it a good stir once it thaws to get the consistency nice and smooth again.

Frosted cupcakes can sit out at room temperature overnight in an airtight container, but I find frosting them right before serving is best.

Nutrition Information



Serving Size


Amount Per Serving Calories 556Total Fat 30gSaturated Fat 18gTrans Fat 1gUnsaturated Fat 10gCholesterol 122mgSodium 417mgCarbohydrates 70gFiber 1gSugar 58gProtein 5g

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Saturday 27th of August 2022

These are amazing! Did you use the same color food coloring for the cup cake and icing?? just checking as I'm wanting to make these but they are two very different greens... Thanks heaps


Sunday 28th of August 2022

Hi Bryar,

Thank you!! That is an excellent question. I use leaf green to color the cupcakes and electric green gel food coloring to color the slime and the frosting. This is the brand I use:

Ive updated the recipe card and links to make this clearer:) Happy baking!

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Friday 24th of December 2021

I managed to make the fondant mouth the whole face quite good....but the lime curd amount can be reduced by a third....I had a lots of leftovers.....and with the frosting was the opposite...I had to make an additional half batch ...and I made a French buttercream.....


Thursday 16th of December 2021

Hi, these cupcakes look gorgeous. However, I have some questions. What is the size of the cupcakes? Regular? And, how do you create the Slimer's mouth? How do you glue things together or do they just stick together? Do they require time to dry? Thank you.


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