• Preheat oven to 350°F and grease a 9x13-inch sheet pan (or line with parchment for easy removal).
• In a small bowl, mix together eggs, milk, and vanilla extract until combined.
• In a stand mixer, combine flour, sugar, baking powder, and salt. Add the butter, one cube at a time to the flour mixture, mixing until the mixture resembles coarse crumbs.
• Pour in half of the egg-milk mixture and the oil, and beat until the batter becomes light and fluffy. Add the remaining egg-milk mixture along with the dry vanilla pudding mix, and mix just until combined. Use a spatula to scrape down the sides of the bowl and make sure everything is evenly incorporated.
• Pour the batter into the prepared sheet pan and smooth the top with a spatula. Bake for 30-35 minutes, or until a toothpick inserted in the center comes out clean. Start checking at 28 minutes and check the center with a cake tester or toothpick. Let the cake cool completely in the pan.

Chocolate Frosting:

• In a mixing bowl, cream together butter, cocoa, powdered sugar, and cream and whip until light and fluffy. You may want to add more cream or milk, depending on consistency. Once cake is cooled, spread evenly with milk chocolate frosting, slice, and serve.
• Store the cake covered at room temperature for up to 2–3 days or in the refrigerator for up to 5 days. For longer storage, freeze unfrosted cake for up to 2–3 months. Let it come to room temperature before serving for the best texture.