Bake It in a Cake

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Ghostbusters Cupcakes!

Who you gonna call? Ghostbuster… cupcakes! These vanilla cupcakes are full of key lime “Slimer” curd and topped with “Stay Puff Marshmallow Man” marshmallow buttercream. They’re finished off with a white chocolate Ghostbusters logo, of course. Perfect for Halloween or a Ghostbusters movie party. Or any day, really. It’s never not a good time for Ghostbusters.

I adapted this lemon curd recipe at Joy of Baking for the Key lime curd. 

For the key lime curd you’ll need:

3 eggs
1/3 c. juice from about 8-10 Key limes
1 t. finely grated or chopped lime zest
3/4 c. caster sugar (granulated will also work)
3 T. unsalted butter 
green food coloring 

For the cupcakes you’ll need:

1 1/2 stick unsalted butter, room temperature
1 1/2 c. granulated sugar
3 eggs
2 t. vanilla
2 t. baking powder
1/2 t. baking soda
1/4 t. salt
2 1/2 c. flour
1 1/3 c. whole milk 

For the buttercream you’ll need:

2 sticks unsalted butter, room temperature
1 7 oz. jar marshmallow cream 
2 c. powdered sugar


First, make the lime curd so it has time to cool. Combine the lime juice, sugar, and eggs in a metal bowl. Heat up a couple cups of water in a medium saucepan over medium heat, and place the bowl on top of that, heating up the mixure and stirring constantly. Keep stirring until the mixture reaches about 160 degrees (F) and starts to thicken. Remove the mixture from the heat and immediately pour it into a fine mesh strainer to remove any pulp or eggs that could have curdled. 

Stir in the butter and the zest, and then add in a couple drops of green food coloring until you get the desired shade of “Slimer” green. Cover with plastic wrap and allow to cool in the fridge while you make the cupcakes.

Pre-heat the oven to 350 degrees (F). 

Cream together the butter and the sugar on med-high speed until fluffy. Add in the eggs, one at a time. Then, with the mixer on low, add the baking powder, baking soda, salt, and vanilla. Stop to scrape down the sides of the bowl, to make sure everything is getting well combined. Stir for another 45 seconds or so and then add the flour and milk, alternating between the two ingredients. The mixture should be smooth and creamy.

Fill the paper-lined cupcake tins about halfway full. Dig out a little crater in the center of the batter and scoop a heaping teaspoon of the lime curd into the center of it. Carefully cover it with more batter (the curd might spread to the edges a little, that’s okay) so the tins are about 3/4 of the way full. 

Bake for about 24 minutes until the cake sets and starts to turn golden brown on the tops and edges.

Remove from the oven and let them cool in the cupcake tins for at least 10 minutes before moving to a wire rack to cool.

For the buttercream, whip together the butter and marshmallow cream until fluffy. Add the powdered sugar, a half cup at time, until you’ve reached the desired tasted and consistency (I use about two cups). 

Frost and eat!

(The Ghostbusters logo was made with melted down white chocolate, put into a pastry bag fitted with a small round tip.)

My cookbook, Bake It in a Cupcake: 50 Treats With a Surprise Inside, is available now at: Amazon.comBarnes & Noble, and!

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