Ingredients
1 package (432g) yellow cake mix (e.g., Duncan Hines®)
240 ml water
80 ml vegetable oil
3 eggs
1 package (85g) lime-flavored gelatin mix (e.g., Jell-O®)
240 ml boiling water
60 ml key lime juice, or more to taste
2 eggs
2 egg yolks
200 g white sugar
180 ml lime juice, or more to taste
4 tsp lime zest, or to taste
2.5 g cornstarch
60 g butter
2 drops green food coloring
1 container (227g) whipped topping (e.g., Cool Whip®)
Directions
Step 1
Preheat the oven to 175°C (350°F) and grease a 23x33 cm (9x13 inch) baking pan.
Step 2
Prepare the cake batter by combining the cake mix, water, oil, and eggs in a large bowl. Beat on low speed until moistened, then increase the speed to medium and beat for 2 minutes. Pour the batter into the prepared baking pan.
Step 3
Bake for 24 to 29 minutes or until a toothpick inserted into the center comes out clean.
Step 4
Prepare the poke filling by dissolving the gelatin mix in boiling water. Add key lime juice and mix well.
Step 5
Use a fork to poke holes all over the cake. Spoon the poke filling over the cake, then refrigerate the cake while you make the curd and frosting.
Step 6
To make the lime curd, whisk the eggs and egg yolks together in a large glass bowl. In a smaller heatproof bowl, combine sugar, lime juice, lime zest, and cornstarch. Place the smaller bowl over a pot of simmering water and stir frequently until boiling (about 5 minutes).
Step 7
Slowly whisk the hot sugar mixture into the beaten eggs. Place the bowl over the pot of simmering water and whisk until the curd coats the back of a spoon (up to 10 minutes). Remove from the heat and mix in the butter until melted.
Step 8
Add food coloring to the curd and mix to achieve the desired shade. Let the curd cool to room temperature for at least 30 minutes. Cover the surface with plastic wrap and refrigerate until completely cool (about 2 hours).
Step 9
Transfer 3/4 of the curd to a separate bowl and add the whipped topping. Fold together until well combined. Spread the frosting over the cake and refrigerate until set (at least 2 hours more).
Step 10
Top the poke cake with the remaining lime curd.