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 14-oz. can sweetened condensed milk
• 1 12-oz. can evaporated milk
• 1 cup heavy cream
• 1 16-oz. jar dulce de leche (milk caramel)