In a separate, larger bowl, whisk together the flour, salt, and powdered milk. Pour the foamy yeast mixture into the dry ingredients. Knead the dough until it's elastic and no longer sticky to the touch. Cover the bowl and set it aside in a warm spot to double in size. This first rise could take anywhere from 1 to 2 hours, depending on the warmth of your kitchen.
Once risen, turn the dough out onto a lightly floured surface. Roll it out, but don't make it too thin; you want your doughnuts to have some height, not be flat. Use a doughnut cutter if you have one, or improvise with a small round bowl or cup for the outer circle and a smaller container (like the mouth of a plastic bottle) for the middle hole. Arrange the cut doughnuts on a baking sheet and let them rise again for another 45 minutes.