Special equipment: an 18-inch piping bag fitted with a star tip and a kitchen blowtorch
For the cookie crumb mixture: Mix together the cookie crumbs and melted butter in a small bowl.
For the cake batter: Preheat the oven to 375 degrees F. Line two 12-cup muffin pans with cupcake liners. Put 1 tablespoon of the cookie crumb mixture in the bottom of each cupcake liner. Set the muffin pans aside.
In the bowl of a stand mixer with a paddle attachment, beat the butter on medium speed until light in color and fluffy, about 6 minutes. Add the sugar and continue beating until uniformly incorporated into the butter; stop the mixer and scrape down the sides of the bowl.
Restart the mixer on low speed and add the eggs one at a time, waiting until each egg is fully incorporated before adding the next. Once the eggs have been added, stop the mixer and scrape down the sides of the bowl to insure that all of the ingredients are incorporated.
Add the vanilla bean paste and blend uniformly. Add the gluten-free baking mix in three additions, alternating with the milk in two additions, fully incorporating each addition into the batter before moving to the next. If needed, stop the mixer after each addition, scrape down the sides of the bowl and resume mixing on low.
Fill the cupcake liners two-thirds full with the batter and bake until the top of each cupcake is slightly springy to the touch and a toothpick inserted in the center comes out clean, 14 to 16 minutes. Immediately turn the cupcakes out of the pans onto a cooling rack and let cool completely.
For the lime filling: In a small bowl, mix 1 tablespoon water with the lemon juice; sprinkle the gelatin over the liquid and let the gelatin bloom and hydrate.
In the bowl of a stand mixer, whip the cream on high speed to medium-firm peaks.
Melt the bloomed gelatin in the microwave just until melted and clear, 15 to 20 seconds; do not overheat as this will kill the gelatin! Stir the key lime curd into the gelatin until all mixed in, and then pour the lime curd into the whipping cream. Mix completely and refrigerate until ready to use.
For the meringue frosting: In a small saucepot, combine the sugar and 1/3 cup water and set over high heat. With a wet pastry brush, wipe down any sugar crystals on the sides of the pot. Cook until the sugar mixture registers 280 degrees F on a candy thermometer.
While the sugar syrup is cooking, beat the egg whites and cream of tartar in the bowl of a stand mixer with a whisk attachment on medium-high speed until the mixture reaches the medium-peak stage. Turn the mixer down to medium low and very, very, very slowly pour the hot sugar syrup into the whipping egg whites. Once all the sugar is added, add the vanilla bean paste and turn the speed up to high. Whip until the mixture is very light and fluffy and the mixing bowl is no longer hot to the touch, about 9 minutes.
Fit an 18-inch piping bag with a star tip and twist and hold the bag right by the tip to prevent the frosting from leaking out. Fold the top of the piping bag over your hand and spoon the meringue frosting into the bag.
To assemble, use an apple corer or paring knife to core out the center of each cupcake. Fill each cupcake with some of the lime filling and top with some of the meringue frosting. Use a blowtorch to lightly toast the top of the meringue.
This recipe was created by a contestant during a cooking competition. It has not been tested for home use.