Set oven to 350 F.
In a medium bowl mix softened butter and sugar until fully combined.
Melt chocolate in microwave or double boiler and once cool to the touch mix into butter and sugar mixture.
Mix in eggs and egg yolks one at a time until just combined.
Mix in oil, vanilla extract, and sour cream.
In a separate medium bowl, sift together flour, salt, baking soda, and cocoa powder.
Add dry ingredients to wet in 1/3 cup increments.
Last mix in water just until combined.
Place Alfajor cookie piece on bottom of cupcake liner.
Fill cupcake liners and put in oven for 18 minutes.
Fill piping bag with half chocolate cream cheese frosting and half dulce de leche.
Once cupcakes are cooled pipe frosting on the tops.
Decorate with Alfajor cookie.