Step 1

Preheat oven to 350° F. Grease and flour 18" x 13" rimmed baking sheet (half sheet pan).

Step 2

In a large mixing bowl add cake mix, eggs, water, oil, buttermilk, and pudding mix. Using an electric mixer, beat one minute on low. Continue beating another minute on medium-high, scraping down the sides of the bowl if needed. (do not over mix)

Step 3

Pour the cake batter into the prepared sheet pan. Bake for 22-25 minutes, or until a toothpick inserted in middle comes out clean. Remove from oven and cool in pan on a wire rack.

Step 4

While the cake is cooling, make the frosting. Using an electric mixer cream butter and cream cheese until well combined and fluffy. Add powdered sugar, gelatin powder, vanilla extract, lemon juice, lemon zest, and 1 tablespoon of cream or milk. Beat until smooth. Add more cream/milk if needed, 1 tablespoon at a time, until desired consistency.

Step 5

Frost cake, garnish with berries and lemon slices if desired. Serve from the pan and enjoy.