1.
Make the Caramel Sauce: In a large-size saucepan over low heat, melt the butter. Add the dark and light brown sugars, milk, and salt, and bring to a boil. Lower the heat to medium and continue to boil for 2 minutes, watching carefully so the mixture doesn’t bubble over the pot. Remove from the heat and let cool. Reserve 3/4 cup for the caramel buttercream. (You’ll have about 2/3 cup left over. Save the caramel in the refrigerator, reheat gently, and drizzle on top of your favorite ice cream.)
