For the flan custard: Preheat the oven to 350 degrees F. In a medium pot over medium heat, add sugar and 1/2 cup water. Cook until the sugar caramelizes and turns an amber color, about 10 minutes, without stirring.
Pour the caramelized sugar into an 8- by 10-inch pan or 10-inch cake pan and let it cool.
In a blender, blend the eggs, cream cheese, condensed milk and evaporated milk. Blend for about 4 minutes.
Pour the mixture into the pan.
Put the pan inside an 11- by 14-inch pan. Put water into the larger pan until almost full.
Bake until it sets and has a slight uniform jiggle, about 1 hour. When done, take the smaller pan out of the larger pan and let it cool.
For the cupcakes: Line cupcake tins with paper liners. Sift together the flour, baking powder, baking soda and salt.
Cream the butter and granulated sugar with an electric mixer until fluffy and light.
Add the eggs, one at a time beating well between each addition. Then add the vanilla and mix until fluffy. Fold in the flour mixture, alternating with the milk. Do not over mix. Portion into the prepared cupcake tins.
Bake for about 20 minutes.
Combine the cream cheese, butter, confectioners' sugar and vanilla in a standing mixer or large bowl.
Mix until smooth and spreadable.
Cut a hole in the top of each cupcake with an apple corer. Fill a pastry bag with the flan. Pipe in enough flan to fill the hole in the cupcake. Top each cupcake with frosting.
