Step 1
Preheat oven to 350° F.
Step 2
Line two cupcake pans with cupcake liners.
Step 3
In the bowl of stand mixer fitted with the paddle attachment, at medium speed, mix brown sugar and butter and beat until light and fluffy, about 2 minutes. Scrape the sides of the bowl as needed. Add eggs, one at a time, and then add vanilla.
Step 4
In a large bowl, whisk together the flour, baking powder, baking soda, and salt.
Step 5
With the mixer at low speed, add flour mixture and buttermilk alternately to butter mixture, ending the process with flour mixture. Mix until just combined.
Step 6
Pour batter evenly amongst cupcake liners to about 1/2 way up the liner.
Step 7
Bake for 20-25 minutes until a toothpick inserted in the center of a cupcake comes out clean.
Step 8
Remove from oven and let them cool in the pan for about 5 minutes. Remove from the pan and allow them to completely cool before adding buttercream.
Step 1
Cream the butter on medium/high in a stand mixer for about 3 minutes until light and fluffy.
Step 2
Add half of the dulce de leche can (reserve the rest for later) and mix until incorporated. Add powdered sugar and salt. Mix at low speed.
Step 3
When all the ingredients have been incorporated, turn the mixer back up to medium/high speed for 2 minutes. The frosting should be thick and fluffy.
Step 4
Put the buttercream frosting in a big pastry bag with a 1M star tip. Frost the cupcakes. Put the remaining dulce de leche in a small disposable pastry bag and cut a small piece from the bottom of the pastry bag. Pipe dulce de leche on top of buttercream. Enjoy.