Beat yolks and icing sugar til fluffy, set aside
Beat butter til creamy, pour in dulce de leche while keep beating until well mixed, set aside
Beat egg whites til fluffy, set aside
Combine flour, spice, and cornstarch
Fold yolks and egg whites, add in dry mixture, stir to combine well
Pour a little amount of batter, grill with upper fire until browning slightly. Pour again, place oreo pieces, without the cream, grill again, repeat until all batter gone.