In the bowl of a mixer, beat the butter over medium speed until creamy. Reduce speed to lowest setting and gently add the confectioners' sugar and baking powder. Continue mixing until everything is incorporated. Add the flour, one cup at a time, and then the egg yolks one at a time; continue beating for a minute. Pour in the water and continue mixing until the dough is smooth and can form a ball (it will take less than a minute). Wrap the dough in plastic wrap and place it in the refrigerator. Let it cool until it hardens enough to be manageable, at least 1/2 hour (the dough can be kept in the refrigerator for up to a couple days).
When ready to bake, preheat the oven to 375 degrees and cover a baking sheet with parchment paper. Place half of the dough on a piece of lightly floured parchment paper, sprinkle some flour over it and then place another piece of parchment paper on top. Use a rolling pin to gently roll out the dough, spreading it evenly about 1/4" thick. Remove the top piece of parchment paper and cut out circles with a round, 3" cookie cutter. With a smaller cookie cutter, make a circular indention in the middle of each cookie, without cutting all the way through the dough (there should be about a 1/4" space between the indentation and the edge). Press the edges of each cookie with a fork as if marking the edges of a pie. Repeat the process with the remaining dough and roll it out again making as many cookies as possible.
Space the cookies at least 1/4" apart on a cookie sheet and bake for about 10 minutes, until they are fully cooked and the bottoms are lightly browned. Remove from the oven and let cool; repeat with the remaining cookies.
Like the nuns: Bring water to a boil in a small saucepan, add pumpkin seeds, simmer about 5 minutes and turn off the heat. Let it cool, stir in baking soda or powder and let it sit overnight. With your hands, rub the pumpkin seeds between your fingers and thumbs to try to release their skins. The skins will float in the water. Carefully pour out the water, cover again with clean water and drain again. With a slotted spatula, place the pumpkin seeds on a clean kitchen towel, rubbing them so the remaining skins come entirely off. Place the seeds in a bowl, cover them with water, rinse and place them on a towel to dry.
Like me: You can skip this part and use normal hulled pumpkin seeds or blanched almonds.
In a medium saucepan, place the sugar and 1/2 cup of water over medium low heat. Cook, keeping a close eye on it, until the sugar has completely melted into the water and appears to be a happily bubbling syrup (which should take anywhere from 8 to 10 minutes). Add the ground pumpkin seeds or almonds and stir well, creating a thick paste. Let the mixture cook for another 3 to 4 minutes—it will thicken and become even more pasty. Turn off the heat, pour in the milk and stir well. It should be thick yet shiny and liquid. Remove the mixture from the heat and let it cool slightly. Use it to top the cookies but before it hardens. If it does harden, just heat the mixture over low heat with a tablespoon of water until it becomes runny again.
Once the cookies are no longer warm to the touch, add the cooled candied pumpkin seed or almond glaze on top with a spoon. 1 to 1 1/2 teaspoons of glaze is more than enough; it spreads as it settles.
I forgo my job in the Washington DC policy research world to research, test, taste, cook, write, teach and talk about Mexican food. Not only because of nostalgia and desire to connect to my roots, but because I love sharing all I learn and I am fascinated by Mexico cuisine's richness and depth.