Preheat your oven to 350°F (175°C). Lightly grease a 9-by-13-inch baking pan with butter or cooking spray.

In a large mixing bowl, prepare the yellow cake mix according to the package directions, adding the required eggs, water, and oil.

Mix until the batter is smooth and evenly combined.

Pour the prepared batter into your greased baking pan, spreading it evenly across the bottom.

Do not bake the cake yet.

In a separate large bowl, combine the pumpkin puree, evaporated milk, heavy cream, eggs, brown sugar, and pumpkin pie spice.

Whisk until the mixture is smooth and the sugar is evenly incorporated.

The filling should have a pourable, custard-like consistency.

Slowly pour the pumpkin mixture over the unbaked cake batter.

Distribute it evenly across the surface without stirring the two mixtures together.

This is where the magic of Pumpkin Magic Cake begins. During baking, the cake and pumpkin filling naturally settle into distinct layers.

Carefully transfer the pan to the preheated oven.

Bake for 50–60 minutes, or until the center is set and no longer visibly jiggly.

A toothpick inserted into the cake portion should come out clean.

The surface may become slightly darker than a traditional yellow cake because of the longer baking time.

Remove the cake from the oven and place the pan on a wire rack.

Allow it to cool completely to room temperature before adding the frosting.

In a medium mixing bowl, combine the vanilla instant pudding mix and pumpkin pie spice.

Pour in the cold milk and whisk until the pudding begins to thicken.

Gently fold in the thawed whipped topping until the mixture becomes smooth, fluffy, and evenly combined.

Spread the frosting evenly over the cooled cake.

For cleaner slices, refrigerate the finished cake for at least 1 hour before serving.

Cut into squares and serve chilled.