Dulce de Leche Cupcakes

I found this recipe, online, and had to try it. However, I like making things easier, so.... Here's the original.
Here's my version:
Dulce de Leche Pumpkin Cupcakes
1 box yellow cake mix
1 1/3 c water
3 eggs
1/3 c pumpkin
1 teaspoon ground cinnamon
1 teaspoon ground ginger
1/4 teaspoon freshly grated nutmeg
Mix all together, and bake per box directions.

Dulce de Leche Buttercream
3/4 cups unsalted butter, softened

1 1/2 Tablespoons heavy cream

1/2 teaspoon vanilla

2 cups powdered sugar

pinch of salt

1/4 cup plus 2 T prepared dulce de leche (I bought La Lechera, from my regular grocery store, in the International aisle.)

Cream together softened butter and powdered sugar on low using an electric mixer. Add cream and vanilla and beat on medium speed until smooth and no lumps appear. Scrape down the sides of the bowl. Add the prepared dulce de leche and beat to incorporate. Frost cooled cupcakes using a knife or a pastry bag and tip.