Make the caramel first so it has a chance to cool down before the donuts are ready. For the caramel: Heat sugar on medium to high heat in a sauce pan, whisking until melted. Be cautious as you do not want the sugar to burn, and be aware of splatter as well. It will be extremely hot!
Once the sugar reduces to a dark amber colored liquid, about 3-5 minutes, add the browned butter. Whisk this bubbly liquid until fully combined and with no remaining lumps. Lower heat to a simmer. Slowly add the heavy cream, and mix until well combined. Remove from heat and allow to cool completely. Caramel will thicken as it cools.
If mixture clumps up at all, simply pop the pan back onto the burner and then the heat up to medium for a minute or two of vigorous stirring. It will come together. Store in an airtight glass container for up to one month in the refrigerator. You can warm the caramel to loosen it up after it has been refrigerated, as it will stiffen. It is still pliable though, so it can be eaten warm or cold.
For the donuts: In a medium bowl, combine the flour, sugar, baking powder, spices, and salt. Whisk to combine. Add melted butter, vanilla and milk, mixing until dough forms. If dough is sticky, add additional flour 1 tablespoon at a time until no longer sticky.
Heat frying oil in a deep pan to 350°. Use enough oil to cover doughnuts without extra room, about 4-5 inches. Be cautious of splatter as oil will be hot. Use a thermometer to ensure temperature remains stable.
Gently place donuts into oil and fry on each side for 1 minutes, or until golden. Remove from oil with a slotted spoon and place on a paper towel lined cooling rack. Allow excess oil to come off, and then roll still-warm donuts in cinnamon + sugar mixture. Drizzle browned butter caramel over donuts, or dunk donut holes into a bowl of it! Enjoy warm or room temperature. Store any leftover donuts in an airtight container at room temperature for up to three days. Donuts are best served day of. Enjoy!
