In the bowl of a stand mixer fit with the dough hook (or large bowl), place 2 cups of flour, yeast, sugar, salt and cinnamon. Mix until combined.
In a glass measuring cup, heat the apple cider and butter until the butter has melted. Set aside until the temperature has come back down to ~125℉.
Once the apple cider / butter mixture is at ~125℉, add it to the dry ingredients and mix to combine. Scrape down the bowl as needed and continue to mix until the flour is incorporated.
Add the additional flour and egg yolks. Mix on medium speed for 5 minutes.
Remove the dough and on a clean surface, knead the dough for 5 more minutes by hand.
Lightly grease your bowl that had the dough in it with avocado oil. Place the dough ball in the bowl and roll it around so there's a little oil all over it. Put plastic wrap on top of the bowl, place it in a cold (OFF) oven for 1.5 hours.
The dough should have doubled in size. Punch down the dough and let it rest for 3 minutes.
Divide the dough in 1/2. Covering the 1/2 you're not working with, with plastic wrap for the time being. On a lightly floured surface, roll out the dough to ~1/2 inch thickness.
Using a donut cutter or glass, cut out the donuts.
If using a glass, use a shot glass to cut out the donut holes. Gather the scrapes and re roll and continue to cut out the donuts until all the dough is used up. Take remaining dough ball in the bowl and roll out and cut as well.
Place on parchment lined sheet pan and cover with plastic wrap. Place back back in the cold (OFF) oven for 45 more minutes until they doubled in sized again.
Meanwhile in a medium sauce pot, fill it with avocado oil with about 2 inches of oil. Using a candy thermometer, heat the oil over medium heat until it reaches 360℉.
Using a slotted spoon, carefully lower the donuts into the oil, 2 large donuts or 6 donut holes at a time. Fry for 1 minute on each side. Make sure the oil doesn't drop below 350℉ and go above 365℉. If it goes below, wait for the temperature to rise before you had more donuts, if it goes below, lower the heat a little.
Place on a sheet pan lined with paper towels. Continue frying the remaining dough. Set aside to cool.