You could try the German Bakery in Villa Maria. From Pedro Clisante in front of Zoilo mercado turn right and go at the end of that street, it's on the corner. They make pretty good pastries I go there for birthday cakes.
you could try K's coffee shop in cabarete, across from the Bon ice cream shop, central cabarete, she makes all kinds of cakes, and probably can make a wedding cake too