Step 1

Heat the oven to 350°F. Lightly coat an 8x8- or 9x9-inch baking dish with unsalted butter.

Step 2

Mix 10 tablespoons melted unsalted butter and 1 box cake mix together with a fork in a medium bowl until combined. Transfer 1 1/2 cups of the mixture to the baking dish. Press down lightly into an even layer to form a thin crust.

Step 3

Beat 16 ounces room-temperature cream cheese, 1/2 cup of the lemon pie filling, 1 large egg, 1/2 cup powdered sugar, and 1/2 teaspoon kosher salt together with a hand mixer on medium speed or a stand mixer fitted with the whisk attachment until light and fluffy, about 2 minutes. Transfer onto the crust and spread into an even layer.

Step 4

Spread the remaining lemon pie filling in an even layer over the cream cheese mixture. Sprinkle the remaining cake mix and butter mixture evenly over the top.

Step 5

Bake until the cake jiggles slightly and is browned around the edges, 40 to 45 minutes. Let the cake cool for at least 45 minutes before serving. Scoop into serving bowls and top with whipped cream or vanilla ice cream if desired.