Preheat your oven to 350°F (175°C) and line a muffin tin with cupcake liners.
In a large bowl, cream together the softened butter and sugar until pale and fluffy.
Add the eggs, one at a time, ensuring each is fully incorporated before adding the next.
Stir in the vanilla extract and dulce de leche until well combined.
In a separate bowl, sift together the all-purpose flour and baking powder.
Gradually add the dry ingredients into the wet mixture, alternating with the milk, starting and ending with the flour mixture.
Fill the cupcake liners about two-thirds full with the batter.
Bake in the preheated oven for 18-20 minutes or until a toothpick inserted into the center comes out clean.
While the cupcakes cool, prepare the frosting by whipping together the heavy cream and remaining dulce de leche until soft peaks form.
Once the cupcakes are completely cooled, frost them generously with the dulce de leche cream.
