Preheat the oven to 350F and grease a 9x13” pan with nonstick baking spray. 

In a large bowl, whisk together the cake mix, 1 cup milk, melted butter, eggs, and 1 teaspoon vanilla extract. 

Transfer the cake batter to the prepared pan and bake for 25 minutes, or until a toothpick inserted into the center comes out clean. 

When the cake has finished, allow it to sit for 10 minutes. Then use a chopstick (or another small round utensil) to poke holes all over the cake. 

In a large bowl, whisk together the remaining 4 cups of milk and 1 teaspoon of vanilla with the banana pudding mix. Whisk for 1-2 minutes, or until the pudding has thickened slightly. 

Pour the pudding evenly over the strawberry cake. Cover the cake and place it in the fridge to chill for 1 hour, or until the pudding is set. The pudding will not fully absorb into the cake– that’s okay! 

Dollop the strawberry frosting over the pudding and swirl the pudding and the frosting together until you have a light pink, creamy topping. It will look like the pudding and frosting won’t mix but keep swirling (about 2 minutes) and they will incorporate into a delicious frosting! 

When you’re ready to serve, decorate with freshly sliced bananas and strawberries (and sprinkles, if using). Keep in mind that the bananas will brown as they sit to make sure to add them immediately before serving. 

Store any leftover cake covered or in an airtight container in the fridge for up to three days.