THE BEST 7-UP CAKE. Try these easy cakes for yourself! The Best 7-Up Cake is a moist lemon cake that is made with a jazzed up boxed cake mix and topped with a delicious lemon icing drizzle. Poke holes all over cake with a straw. Spread cool whip over top and serve cool. Cool, and invert (turn over) cake onto a tray large enough to hold the cake. 1 / 15. Put in refrigerator to cool and set for 4 hours. When my family is planning a get-together, I can count on three or four people asking if I’m bringing this chocolate peanut butter poke cake. To make the topping: Dissolve the jello powder completely in boiling water, with the sugar, then add in the COLD water; mix well. When cooled, poke holes throughout cake using a chopstick or fork (chopsticks better). Bake for 30-35 minutes, or until cake tests done. Recently I shared my recipe for DOUBLE FUDGE COCA-COLA CAKE and then I realized, I couldn’t share the Coca-Cola Cake without also sharing the 7-Up Cake. Transfer cake batter to a prepared baking pan. Peanut Butter Chocolate Poke Cake. Pour mixture evenly over top of cake allowing it to "soak" through the holes you made. These poke cake recipes are extra moist and delicious thanks to additions like coffee, caramel and even a bit of rum. Mix jello powder with 1 and 1/4 cups of 7-up soda.