Step 1

Preheat oven to 350°F

Step 2

Place the butter in a large microwave-safe mixing bowl; microwave in 20-30 second intervals until melted. Mix in the granulated and brown sugars. Add the sour cream, eggs, cinnamon, and vanilla; whisk until all is combined. Add the apples to the bowl; stir to coat completely in the butter mixture.

Step 3

Sprinkle the flour, baking soda, and salt over top of the apple mixture; mix well until all of the flour is absorbed. Pour the batter into a greased 9x13-inch baking dish.

Step 4

Bake 55 minutes or until a toothpick inserted into the center of the cake tests clean. Loosely cover with aluminum foil halfway through baking if the cake appears to be browning too quickly. Cool 15 minutes before slicing and serving.