Activate the yeast. In a bowl, mix warm milk, yeast, and 1 tablespoon of the sugar. Let it sit for 5–10 minutes until foamy. If nothing happens, your yeast may be expired or the milk too hot.
Make the dough. In a large mixing bowl, whisk remaining sugar, salt, and 2 cups of flour.
Add the foamy yeast mixture, eggs, vanilla, and softened butter. Mix until combined, then add remaining flour a little at a time until a soft, slightly sticky dough forms.
Knead until smooth. Knead by hand on a lightly floured surface or with a dough hook on medium-low for 6–8 minutes. The dough should be smooth, elastic, and still a touch tacky.
Avoid adding too much flour.
First rise. Place dough in a lightly oiled bowl, cover, and let rise in a warm spot until doubled, about 1–1.5 hours. A slow, steady rise keeps donuts tender.
Roll and cut. Turn dough onto a floured surface. Roll to about 1/2 inch (1.25 cm) thick.
Use a 3-inch donut cutter (or two round cutters) to cut donuts and holes. Gently re-roll scraps as needed.
Second rise. Place cut donuts on parchment-lined trays. Cover loosely and rise 30–45 minutes, until puffy and slightly jiggly.
They should not double again, just look airy.
Heat the oil. Pour 2–3 inches of oil into a heavy pot. Heat to 345–350°F (174–177°C). Keep a thermometer clipped to the side for accuracy.
Fry in small batches. Carefully lower 2–3 donuts into the oil.
Fry about 45–60 seconds per side until light golden. Don’t let them brown deeply—pale gold keeps them soft and “melt-in-your-mouth.”
Drain properly. Lift with a slotted spoon and drain on a wire rack set over a sheet pan. Keep the oil at temperature between batches.
Fry the holes too—about 30–45 seconds per side.
Make the glaze. Whisk powdered sugar, vanilla, pinch of salt, and 6 tablespoons of milk until smooth and pourable. Add more milk by teaspoons until it runs off a spoon in a ribbon. Thinner glaze = more translucent sheen; thicker glaze = sweeter coat.
Glaze while warm. Dip each warm donut into the glaze, flip to coat, then lift and let excess drip back into the bowl. Place on the rack to set for 10–15 minutes.
For extra shine, glaze twice.
Serve fresh. Donuts are best within a few hours. They’ll be soft, airy, and gently sweet with that signature finish.