Step 1

Preheat oven to 350°F. Line two 9-inch cake pans with parchment paper circles and spray with baking spray.

Step 2

Cream butter and sugar. Add eggs one at a time. Add vanilla extract.

Step 3

Add flour, baking powder, and salt alternately with sour cream and milk.

Step 4

Bake for 30-35 minutes. Cool in pans for 10 minutes before turning out onto a wire rack to cool completely. (Or bake in 3 pans for 23-30 minutes.)

Step 5

Combine butter, sugar, and evaporated milk in a large saucepan over medium heat, stirring until melted.

Step 6

Reduce heat to medium-low and cook for about 1 1/2 to 2 hours, stirring occasionally to make sure it doesn't burn, until the mixture reaches 240°F (soft-ball stage) on a candy thermometer clipped to the side of the pan. It should have thickened and turned a beautiful caramel brown color.

Step 7

Remove from the heat and stir in the vanilla extract. Let the caramel icing cool for about 20 to 25 minutes before icing the cake so it can set up more. To thicken it even more, you can beat it with a sturdy wooden spoon for 20 to 25 minutes until it reaches a glossy, smooth, thick consistency that is spreadable or you can actually transfer the mixture to a mixing bowl and beat with the paddle attachment for more of a frosting than a caramel icing. If the icing gets too thick, add just enough milk to make it spreadable again.

Step 8

Frost the cake layers with the caramel icing, then chill to set.