Slime-Filled Cupcakes from the Black Lagoon

Last year, I celebrated Halloween with a batch of Vampire Cupcakes. The cupcakes were filled with a gooey, thick cherry pie filling that made the cupcake look like it was bleeding when you bit into it. I planned on baking more this year, but couldn’t help but wonder if I could take the concept in another direction to make another Halloween treat to complement it. I started by thinking of replacements for the oozy blood filling and came up with the idea to put a bright-green slime filling inside. After all, what could be oozier than slime?

I started out by making a batch of lime curd and using food coloring to give it a very bright green color, as lime curd on its own tends to be a fairly pale yellow. The curd needs to be made before the cupcakes so that it has time to cool and set up in the refrigerator before you use it. I think that lime is an appropriate slime flavor, but you could certainly dye lemon curd bright green, as well.

I used vanilla cupcakes as a base, hollowing them out via my usual method for filling cupcakes once they had cooled. The cupcakes were moist and not too sweet, which meant that the cake didn’t detract from the tartness of the filling, just balanced it out. I used a spoon to drop a dollop of lime “slime” into each hollow, as the curd flows much better than your average cream filling and does not need to be piped in.

I dyed vanilla frosting a light green to finish the cakes. You don’t have to dye the frosting green for these cupcakes, of course, although I think that the green adds to the general swampiness of the cupcakes and makes them look a little more Halloween-appropriate than a plain white frosting would. If anything, I would experiment with different colors of frosting, like black or brown. You can buy black dye at baking/craft stores, but adding in some red or blue with the green can give the color a darker tone. Chocolate frosting would not be a great choice because the flavor could overwhelm the slime filling, even though it would give a nice earthy look to the cake.

Slime-Filled Cupcakes from the Black Lagoon
Slime (Lime Curd) Filling:
2/3 cup strained fresh lime juice
3/4 cup sugar
2 large eggs, room temperature
10-12 drops green food coloring

In a small sauce pan, over medium heat, dissolve sugar into lime juice.
Lightly beat eggs in a small/medium bowl. Whisking constantly, slowly trickle hot lime/sugar syrup into the eggs. Beat for about 1 minute, until well combined, then transfer back into the saucepan. Cook over medium heat, stirring frequently, until curd starts to bubble and is thick. Stir in the food coloring while the curd is cooking. Remove from heat and transfer to a heatproof bowl.
Cover with plastic wrap and refrigerate until cold.
Makes about 1 1/3 cups.

 Black Lagoon (Vanilla) Cupcakes:
1 1/3 cups all purpose flour
1 tsp baking powder
1/4 tsp salt
1 cup sugar
1/3 cup butter, melted and cooled
2 large eggs
1 tsp vanilla extract
3/4 cup milk (low fat is ok)

Preheat oven to 350F. Line a 12-cup muffin pan with paper liners.
In a large bowl, whisk together flour, baking powder, salt and sugar.
In a medium bowl, whisk together cooled, melted butter, eggs, vanilla and milk. Pour into flour mixture and stir until just combined and no streaks of flour remain.
Distribute batter evenly into prepared muffin cups.
Bake for 16-19 minutes, until a toothpick inserted into the center of a cupcake comes out clean.
Cool completely on a wire rack before filling and frosting.
Makes 12-cupcakes.

 Filling and Frosting
(A photo how-to of the assembly method can be found here.) Take a cooled cupcake and, using a small pairing knife, cut a cone of cake (1-inch across by 1-inch deep) out of the top. Trim off the pointy end of the cone, leaving a flat circle of cake. Set aside the circle and discard (or eat) the rest of the cone. Repeat this process for all the cupcakes.
Take the slime filling and spoon about tablespoon into each cupcake cavity, filling it almost to the top with lime curd. Top off with the flat circle of cake you just removed to seal the hole and hold the “black lagoon” filling in place.
Once all the cupcakes are filled, they can be frosted just as ordinary cupcakes.

Swampy Vanilla Frosting
1/2 cup butter, softened
1 tsp vanilla extract
2-3 cups confectioners’ sugar
2-4 tablespoons milk
green food coloring

Cream butter with an electric mixer until soft. Add vanilla and gradually add in sugar until most has been incorporated. Mixture will look a bit sandy. Add in milk as necessary (start with 2 tbsp), along with any remaining sugar, until frosting reaches a thick, but easy-to-spread consistency. Add green food coloring until desired green color is reached. Add in a few drops of red with the green for a brownish color, or a drop or two of blue to deepen the green.