Preheat oven to 350°F and place paper liners in muffin tin or grease and flour muffin tins.

In a medium sized bowl, sift together flour, baking powder, and salt. Set aside.

Cream the butter with an electric mixer for 1 minute. Add the sugar and mix for 2 more minutes until light and fluffy. Add the vanilla.

Add the eggs one at a time, mixing well after the addition of each egg.

Alternatively add the dry ingredient mixture and milk to the sugar mixture, mixing well after each addition and be sure to scrape down the sides of the bowl.

Fill cupcake liners about 3/4 full.

Bake for 15-20 minutes, until a toothpick comes out clean when inserted into the center of a cupcake. Cool for about ten minutes in the muffin tins and then remove to a rack to cool completely.

Once cupcakes are cooled, core them (save the tops for bite sized snacks). Set cupcakes aside to make the buttercream. 

In the bowl of an electric mixer fitted with a paddle attachment or in a large bowl using a hand held mixer, cream the butter for one minute. Add the sifted powdered sugar and beat on medium for 3-4 minutes, until creamy. Add 1/2 tablespoon of the heavy cream or milk. Slowly beat in the dulce de leche a little bit at a time. Beat in the vanilla followed by the salt. 

If buttercream is too thin, add more powdered sugar, if it is too thick, add more milk or heavy cream until it is the consistency you desire. To firm buttercream up a bit more before piping, cover it with plastic wrap and refrigerate it for 20-30 minutes. Pipe the frosting on top using a wide star tip or scoop it on using an ice cream scoop!