Combine the powdered milk, granulated sugar, and powdered sugar in a large bowl. Set aside.
In a large pan, toast the flour on the stove over medium low heat. Watch closely, stirring occasionally. You want the flour to get a light beige to tan color, and become fragrant.
Add the toasted flour to the milk and sugar mixture, and stir to combine. Set aside.
In a medium saucepan on the stove over medium heat, brown both cups of butter. Watch closely, stirring occasionally. The butter will melt, and the mixture will pop and bubble. Once it begins to foam, and smell sort of nutty, you will see specks of toasty brown milk solids at the bottom. This is when you remove from the heat. Cool slightly, and add vanilla to the butter mixture.
Take browned butter mixture and pour it over the flour/milk/sugar mixture. Mix with a large wooden spoon, or by hand, to incorporate the butter. You are looking for the consistency of wet sand, fit to mold into a sand castle.
Press into a Polvoron mold, store into an airtight container, and place in the fridge or the freezer to set. Another option is to put it in jars and enjoy it with a spoon. Lasts for 3-5 days in an airtight container at room temperature or up to 4 months in freezer.
