Place 1/3 of a can of dulce de leche in the freezer. Spread the sides of 4 small mugs with a little dulce de leche; refrigerate for 10 minutes.
Blend evaporated milk and remaining dulce de leche until well combined; add flour, baking powder, brown sugar, oil and egg. Blend well.
Place small amount of mixture in each of the cups; divide the frozen dulce de leche between the cups. Add rest of the mixture to the cups, filling 1/2 full. Microwave each for 2 minutes in 40-second intervals or until cooked.