Preheat oven to 350F degrees. Gather your ingredients so that you have everything you need close at hand on the counter or table. Spray an oblong baking pan with baking spray.
Prepare the Cake
In a large mixing bowl, combine the white cake mix, large eggs, vegetable oil, buttermilk, and water. Beat on low for 30 seconds. Increase speed to medium and beat for two minutes, scraping the bowl occasionally.
Pour the cake batter into the prepared baking pan.
Bake in preheated oven for 25-30 minutes until a toothpick inserted into the center comes out clean. Remove from oven and allow to cool for 15-20 minutes.
Make the Gelatin
While the cake cools, prepare the strawberry gelatin. Boil water and pour 1 cup over the gelatin. Stir until it dissolves.
Poke the cake in 1-inch intervals with the tines of a fork or the end of a wooden spoon (which is what I used).
Spoon the strawberry gelatin over the top, making sure to target the holes, but covering the entire cake.
Cover the cake and refrigerate for 1-3 hours.
Marshmallow Whipped Topping
Once the cake has cooled completely and the gelatin has set up, prepare the whipped topping.
Place the thawed whipped topping into a medium bowl. Add to this the marshmallow cream and vanilla bean paste. Whisk together until combined, but do not overmix.
Spread half of the topping over the cake. (See note at bottom of post.)
Cover and refrigerate until ready to serve.
To serve, slice the cake into 12-16 pieces. If desired, garnish with fresh strawberries. This cake will serve up to 16 people.
Notes
*This topping will actually make enough for two cakes. If desired, you may opt to make half a recipe for the topping or make the full recipe and use half as a fruit dip with strawberries, blackberries, bananas, and apples.