01 - Preheat oven to 350°F. Grease and flour three 8-inch cake pans and line bottoms with parchment paper.
02 - Whisk together flour, baking powder, and salt in a medium bowl.
03 - Beat butter and sugar in a large mixing bowl until light and fluffy, about 3-4 minutes. Add eggs one at a time, then vanilla extract.
04 - Alternately add flour mixture and milk to the batter in three additions, beginning and ending with flour. Mix until just combined.
05 - Divide batter evenly between prepared pans. Bake for 28-32 minutes until a toothpick inserted in the center comes out clean. Cool for 10 minutes in pans, then turn out onto wire racks to cool completely.
06 - Combine sugar and water in a heavy saucepan over medium heat, swirling until sugar dissolves. Increase heat to medium-high and cook until golden amber, 7-10 minutes. Remove from heat and whisk in butter, then cream and salt. Cool to room temperature.
07 - Beat butter until creamy. Gradually add powdered sugar, then caramel sauce, vanilla, and salt. Beat until light and fluffy, 2-3 minutes.
08 - Place one cake layer on a platter. Spread with a generous layer of caramel frosting. Repeat with remaining layers. Frost top and sides. Drizzle extra caramel sauce over top for a glossy finish.
09 - Chill for at least 30 minutes before serving for cleaner slices.