1. Preheat oven to 350°F (175°C). Grease a 6-cavity donut pan well.
2. In a bowl, whisk flour, sugar, baking powder, salt, and nutmeg.
3. In another bowl, mix milk, oil, vinegar, and vanilla. Let sit 2 min (it will curdle slightly—this is fine!).
4. Pour wet into dry; stir just until combined (small lumps OK—overmixing = tough donuts).
5. Spoon or pipe batter into pan, filling each cavity ¾ full (a piping bag or zip-top bag works great).
6. Bake 10–12 min until springy to touch and a toothpick comes out clean.
7. Immediately—while hot—remove donuts, brush lightly with melted butter or oil, then roll in cinnamon-sugar.
8. Cool on a rack. Best served same day (they’re at peak tenderness within 4 hours!).

PREP TIME & NUTRITION (per donut, makes 6):
Prep Time: 10 min | Cook Time: 12 min | Total Time: 25 min | Servings: 6 | Calories: 190 | Net Carbs: 32g | Fats: 6g | Protein: 2g