Dulce de Leche Cake

Ingredients

• 2 tsp. butter
• 1 tbsp. plus 2 cups flour
• 2 tsp. baking powder
• 1 1⁄2 tsp. fine salt
• 6 eggs, at room temperature, separated
• 1 1⁄4 cups sugar
• 1⁄2 cup whole milk
• 1 1⁄2 tbsp. dark rum
• 1 tbsp. vanilla extract
• 1 cup heavy cream
• 1 (14-oz.) can sweetened condensed milk
• 1 (12-oz.) can evaporated milk
• 1 (16-oz.) jar dulce de leche (milk caramel)