Start by dissolving yeast in lukewarm milk. Let it rest for 5-10 minutes.
In a bowl of a standing mixer add 6 cups of flour, sugar, salt and lemon zest. Using a dough hook attachment start to mix on low speed.
Slowly pour in the milk with yeast. Add eggs and butter cut in cubes.
Increase the speed and knead the dough for about 10 minutes until it starts to wrap lightly around the dough hook and come off the sides of the mixer bowl.
The dough should be soft but NOT sticky.NOTE: If the dough doesn’t come together or it’s too sticky add another ½ cup of flour and a few more table spoons at a time if needed.
Transfer the dough into a large clean bowl, cover with a linen towel and let it rise in a warm, draft free place. It’ll take anywhere between 1.5 to 2 hours at 75-80F and it’ll take much longer in a cooler place.
Once the dough has almost tripled in size, turn the bowl upside down and let the dough come out in a floured surface. Work the dough with your hands for a minute or two, dust with more flour if needed.
Using a dough scraper cut off a fourth of the dough and with a rolling pin roll it out approx ⅓ -¼ of an inch thick.
Using a doughnut cutter cut out the doughnuts and place them on a well floured surface leaving enough space in between. Cover them with a dry linen/kitchen towel and let rise (always in a warm place) for about an hour.
In a deep pan preheat vegetable oil suitable for frying. The best temperature to start frying the doughnuts is about 350F. You can measure it with a kitchen thermometer.
But if you don’t have one try frying a small piece of the dough first. If it comes up floating in less than 5 seconds the oil is ready.
Once oil is heated turn the temperature on medium low to prevent oil from overheating.
Fry fritelle for a few minutes on each side continuously covering them with hot oil when frying. Once they’re lightly brown on both sides discard on paper towel to absorb excess oil.
Dip each doughnut quickly in fine sugar. Serve hot, warm, cold or re-heated.