Preheat oven and prepare cake pans. Mix dry ingredients and creamed butter, eggs, sugars, sour cream, milk, oil, toffee bits, and pecans to make the batter.
Divide batter into pans and bake at 350°F (175°C) for about 30-35 minutes. Let cakes cool completely.
Beat softened butter, cream cheese, vanilla, salt, and powdered sugar until smooth. Mix in caramel sauce.
Spread frosting between layers and over the top. Decorate with additional pecans and toffee bits if desired.
Chill the cake before serving to set the frosting.
Notes
Ensure to fully cool the cakes before frosting to prevent melting.