Preheat the oven to 350 degrees and prepare cupcake pan by placing the cupcake liners for approximately 24-30 cupcakes. 

In the bowl of a stand mixer, cream butter and sugar. 

Add in the egg whites, oil, baking powder, salt, vanilla and milk.  Combine well. 

Add the flour and mix thoroughly.  Stop the mixer, scrape the sides of the bowl and mix again. 

Add in half the can of dulce de leche and gently swirl into the batter by hand. 

Divide cupcake batter using an ice cream scoop into the cupcake tin, filling half way. 

Bake in preheated oven for 14-16 minutes or until lightly browned or when a toothpick comes out clean from the center of the cupcake. 

Allow cupcakes to cool completely on a wire rack before decorating.

To make the dulce de leche frosting, combine the softened butter and powdered sugar until mostly combined in the bowl of a stand mixer.  

Into the butter mixture, add in the salt, vanilla and 2 tablespoons of milk and a little less than half the dulce de leche - retain approximately 2 T. worth to drizzle over the frosting later.  

Beat frosting until smooth - scraping the sides frequently and adding additional milk only if needed to bring the frosting together.  

Transfer the frosting to a piping bag fitted with a large star tip.  Gently pipe a spiral cone shape of frosting on each cupcake. 

Place dulce de leche in a microwave safe bowl for about 15-20 seconds or until softened.  

Using a spoon, carefully drizzle the extra dulce over each of the finished cupcakes.