Activate Yeast in Milk:

Scatter the active dry yeast over the warm milk. Give it a stir and let sit until the yeast dissolves and becomes active, roughly 3 to 5 minutes.

Whisk Dry Ingredients:

In a bowl, whisk together the flour, 3 tablespoons sugar, and salt until well combined.

Mix and Rest Dough:

Once the yeast has dissolved, pour the milk mixture and egg into the flour. Stir until the dough begins to come together, then knead until no dry patches remain. Cover and allow to rest in a warm spot for 20 to 30 minutes. (A stand mixer may be used.)

Knead in Butter:

After the rest, incorporate the softened butter and knead until it is fully worked in and the dough feels smoother. Form into a ball, cover, and let proof in a warm area until it doubles in volume, approximately 45 minutes to 1 hour.

Prepare Sheet Pan:

While the dough proofs, prepare a sheet pan by lining it with parchment paper.

Divide Dough into Six:

Once doubled, turn the dough out onto a clean surface. Knead briefly to release gas, then cut into 6 equal portions.

Shape Twisted Donuts:

Shape each portion into a thin rope about ½ inch thick and 12 inches long. Grasp both ends and twist in opposite directions. Lift the rope by the ends so it coils onto itself. Pinch the ends together and adjust the twists as desired. Place on the prepared pan, leaving at least 1 inch between pieces. Repeat with remaining dough. Dust with flour if sticky.

Proof Shaped Donuts:

Let the shaped dough rest in a warm place until doubled, about 45 minutes to 1 hour.

Mix Cinnamon Sugar:

In a shallow bowl, combine the ⅓ cup sugar and cinnamon; set aside.

Heat Oil to 325°F:

When the donuts are almost doubled, heat oil in a deep fryer or pot to 325°F (165°C), using about 1 to 2 inches of oil. Keep the oil temperature between 300°F (150°C) and 325°F (149-163°C).

Snip Parchment Around Donuts:

While the oil heats, snip the parchment around each donut with scissors, leaving a small piece attached at the ends to help with handling.

Fry Donuts Until Golden:

Using the parchment, gently lower the donuts into the hot oil without deforming them. Fry in batches if necessary. After a few seconds, pull the parchment out of the oil. Continue frying until both sides are golden brown, about 3 to 4 minutes total. Transfer to a rack or paper towels to drain.

Toss in Cinnamon Sugar:

While still hot, toss the donuts in the cinnamon sugar. Let them cool a bit before serving.