Preheat oven to 350. Put cupcake liners in muffin tin.

In a medium sized bowl, sift together flour, cornmeal, salt, baking powder and baking soda.

Set aside.

Set the eggs out on the counter to come to room temperature while you beat the butter and sugar.

In the bowl of a stand mixer, beat butter on medium speed until softened and pliable.

Add the sugar and beat until light and fluffy, about 4 minutes.

Add the avocado and beat another minute to incorporate.

Scrape down the sides of the bowl to ensure that everything is thoroughly mixed.

Add the eggs one at a time, beating 1 minute after the addition of each egg.

Beat in vanilla extract.

Reduce the mixer speed to low and add half of the flour mixture, all of the buttermilk, and then the rest of the flour mixture.

Beat just until combined.

Pour into cupcake liners until they are about 3/4 full.

Put a dollop (about a tsp) of dulce de leche on top of each liner full of batter and swirl around with a butter knife.

Bake for 15-20 minutes or until a toothpick inserted comes out clean.

Let cool for five minutes in pan and then remove to a wire rack.