Preheat oven to 350 F. Lay out 1 of the pastry sheets on a large cutting board. Find a lid or glass that is 2 ½ inches in diameter, place the lid on the dough, press hard, then trace the circle with a paring knife. You will be able to get 9 circles from each sheet. Gather the dough scraps, roll it out flat with a rolling pin, and cut out 6 more circles.
Spray a mini muffin tin with cooking spray. Press each dough circle into the muffin mold, and press to secure onto the sides.
In a medium bowl, combine the hot water, and the sugar. Stir to dissolve. Let it cool for 5 minutes, then add the eggs, milk, and vanilla to the bowl, and stir well with a whisk.
Pour the egg mixture into the prepared mini muffin tin. Bake for 30 minutes, or until the tops are starting to brown, and they are getting puffy.
Pull the muffin tin out of the oven, then carefully take them out of the muffin tin, and set them on a cooling rack for 20 minutes before serving.