In the bowl of a standing mixer, whisk the yeast and 1/2 cup of the milk until the yeast has dissolved. Let stand 5 minutes, then stir in 1 tbls. of the sugar and 1/2 cup of the flour, forming a thin batter. Cover this sponge with plastic wrap and let rest at room temp for 20-30 minutes, until bubbles form.
Reheat the remaining 1/2 cup milk to lukewarm. Stir the warm milk, buttermilk, nutmeg, lemon zest and teh remaining 1/4 cup plus 1 tsp sugar into the sponge. Place the remaining 3 1/2 cups flour and the salt on the top of the sponge. Put the bowl on the mixer fitted with the paddle attachment. Mix on low speed for 2 minutes or until the dough comes together. Scrape down the bowl and the paddle and change to the dough hook. Increase the speed to medium and knead the dough for 5 minutes.
Turn the speed down and add the softened butter, 1 tablespoon at a time. Stop the mixer and scrape down the sides. Mix for 5 minutes or until the dough comes together and is smooth. Scrape the dough from the sides of the bowl, cover with plastic wrap and set it aside to rise at room temperature until doubled in volume, 1 1/2 to 2 hours.
Line two 12 x 17 inch half sheet pans with parchment and lightly dust with flour. When the dough is ready, turn it out onto a flat surface, dusted with flour and roll it out to a 10″ square with a thickness of 1/2″. Wrap the dough in plastic and put in freezer for 20-30 minutes. Using a 2 1/2″ doughnut cutter, cut out the doughnuts and the holes. Dip the cutter in flour each time. Place doughnuts and holes on the sheet pans. Cover with lightly sprayed plastic wrap and let rise 30 minutes.
In a deep heavy skillet (I used my Le Creuset), heat 3″ of oil over medium heat to 350*. Carefully slide 4 doughnuts at a time into the hot oil. Brown on one side, then the other, using a slotted spoon to flip. Drain them on paper towels.
1. Cinnamon sugar – 1 cup sugar mixed with 1 1/2 Tbls. cinnamon. Coat these right away when doughnuts are still a little wet.
2. Chocolate – melt 4 oz. of bittersweet chocolate with 4 oz. unsalted butter in a bowl over simmering water.
2. Glaze – 2 cups of powdered sugar mixed with 1/4 cup milk and 1 tsp. vanilla
Eat these right away!