Preheat the oven at 390°F.
In a food processor, pulse the almonds until fine.
In a stand-alone mixer fitted with a paddle attachment, combine sweetened condensed milk, eggs, and almonds, beating at medium speed.
Add the butter to the mixture, 1/4 cup at a time, beating at medium speed until the ingredients are combined. The mixture will have small bits of butter throughout.
Add the flour, 1 cup at a time, beating at low speed.
Add the baking powder and beat at low speed until combined. The dough will have a sticky consistency.
With some flour in the palm of your hands, pinch a portion of dough and roll it between your palms to form a ball the size of a golf ball.
Place the ball on a baking sheet lined with parchment paper. Repeat the process with the rest of the dough, leaving a couple of inches between each cookie.
Bake in the preheated oven for 10 to 12 minutes. The cookies will crack slightly on the top.
Insert a toothpick within the cracks to test for doneness. If the cookie is done, the toothpick will come out clean.
While still warm, roll the cookies in a generous amount of confectioners’ sugar. Serve.