These sourdough donuts use a risen dough and are topped with an amazing browned butter frosting!
Place all of the ingredients for the dough in the bowl of a stand mixer.
Using the dough hook, knead for 10 minutes on medium-low (3 out of 10 on my mixer).
Transfer the dough to a greased large bowl. Cover and allow to ferment at room temperature until doubled, about 8-12 hours, depending on how warm your kitchen is.
Turn your oven on to its lowest setting, and once it's preheated, turn it off and leave the door closed.
Place the dough on a large piece of parchment paper. Using your hands (grease if necessary) pat the dough out into a rectangle until it's about ½ inch thick.
Using a biscuit cutter, mason jar, glass, or donut cutter, stamp out rounds of dough. Using the smallest biscuit cutter in your set or a small bottle, stamp out donut holes.
Arrange the donuts and holes on the parchment paper about and inch apart and transfer them, parchment paper and all, onto a flat baking sheet. Place in the warm oven and allow to raise until quite puffy, about 2-4 hours.
Line a rimmed baking sheet with paper towels.
Heat a couple of inches of avocado oil in a 12 inch cast iron skillet to 365°F - 375°F. Drop 4-5 of the doughnuts carefully into the hot oil. Cook for 1 minute on each side. You don't want them to be super pale or really dark. A nice golden brown is perfect.
Keep and eye on the temperature and make sure the oil doesn't drop below 350°F or rise above 375°F.
Remove the cooked doughnuts to the paper towel lined baking sheet.
Repeat the cooking process with the remaining donuts, then the donut holes. Some of the holes may refuse to flip over - that's okay!
Allow the donuts to cool until just barely warm before frosting.
Place the powdered sugar, browned butter, cream, vanilla, and salt in a medium bowl. Whisk until smooth. Add more cream to achieve a consistency that's between a spreading and pouring consistency.
You can either spread the frosting on the donuts with an offset spatula, pour the glaze on top of them, or dunk them. I personally find that dunking is the least effective.
These donuts are best served immediately, but you can store them in an airtight container in the fridge if needed. Best if reheated, of course!