STEP 1:
For the caramel sauce, swirl sugar and water until sugar is fully immersed. Place saucepan over heat until the sugar dissolves and turns an amber color.
STEP 5:
Add the sour cream and vanilla and beat. Add half of the dry ingredients to the batter. Stream in the milk and in the rest rest of the dry ingredients.
STEP 6:
Distribute batter among 3 prepared cake pans. Bake at 350F for 30 min. Remove from oven and invert them onto a tea towel. Cool before frosting.
STEP 8:
Pipe a border of frosting along the edge of the first layer of cake and fill in with the caramel sauce. Pipe another thin layer of frosting on top of the caramel.