Hi Pamela. I am not sure about Heloise's recipe, but here is a basic rainbow poke cake recipe.

RAINBOW POKE CAKE

Poke Cake is made by adding gelatin to holes made in the cake.

2 completely baked and cooled cake layers, round or square

2 cups boiling water
2 (3 ounce each) packages of gelatin, your choice of flavors and/or colors
8 or 12 ounce container whipped topping, thawed

Place cake layers, top sides up, in 2 clean cake pans. Pierce cake layers with fork every 1/2-inch.

Prepare each package of gelatin separately. Completely dissolve gelatin powder with 1 cup boiling water. Stir for 2 minutes.

Carefully pour one gelatin over one cake layer and the other over the second layer. Refrigerate for 3 hours.

Dip 1 cake pan in warm water 10 seconds; unmold onto serving plate. Spread with 1 cup of whipped topping.

Unmold second cake; carefully place on first layer. Frost top and sides of cake with remaining whipped topping.

Refrigerate for at least one hour. Decorate, if desired.