Key Lime Poke Cake

Preheat the oven to 350 degrees F (175 degrees C). Grease a 9x13-inch baking pan.

Combine cake mix, water, eggs, and oil in a large bowl; beat with an electric mixer on low speed until moistened. Increase speed to medium and beat for 2 minutes. Pour batter into the prepared baking pan.

Bake in the preheated oven until a toothpick inserted into the center comes out clean, 24 to 29 minutes.

Dissolve gelatin mix in boiling water. Add key lime juice and mix well.

Use a fork to poke holes all over the cake. Spoon gelatin-key lime mixture all over cake. Refrigerate until completely cool and ready to use.

Meanwhile, whisk eggs and egg yolks together in a large glass bowl. Combine sugar, lime juice, lime zest, and cornstarch in a smaller heat-proof bowl.

Place bowl with the sugar mixture over a pot of simmering water. Stir frequently, scraping down the sides with a rubber spatula to avoid scorching, until mixture comes to boil, about 5 minutes.

Slowly whisk hot sugar mixture, little by little, into the beaten eggs. Place bowl over the pot of simmering water and whisk until curd coats the back of a spoon, up to 10 minutes. Remove from heat; mix in butter until melted.

Drop food coloring into the curd and mix to achieve your desired shade. Let cool to room temperature, at least 30 minutes. Cover surface directly in plastic wrap and refrigerate until completely cool, about 2 hours.

Transfer 3/4 of the curd into another bowl. Add whipped topping and fold together until well combined. Spread frosting over the cake. Refrigerate until set, at least 2 hours more. Top with the plain curd.