Start by mixing together the heavy cream, whole milk, and granulated sugar in a small bowl. Heat the mixture in the microwave in 20-second intervals until it reaches around 110 degrees Fahrenheit. Be careful not to overheat it; if it gets too warm, let it cool back down to 110 degrees before proceeding.
Next, add the dry active yeast to the warm liquid and let it stand for about 10 minutes until it becomes frothy. This step is crucial as it activates the yeast, which helps the donuts rise.
Meanwhile, combine the all-purpose flour and kosher salt in the bowl of a stand mixer. Stir them together gently to evenly distribute the salt.
Once the yeast mixture is frothy, pour it into the bowl with the flour. Using a dough hook on speed 2, knead the mixture for about 5 minutes until it becomes smooth and elastic. You’re looking for a soft, pliable dough.
Lightly oil a large glass bowl and scrape the dough from the mixing bowl, shaping it into a ball. Place it in the oiled bowl and turn it to coat all sides. Cover the bowl with a clean kitchen towel and let it rise in a warm place for 1 to 2 hours, or until it doubles in size.
After the dough has risen, turn it out onto a lightly floured surface. Roll it out to about ½ inch thick. Use a donut cutter or a 3-inch round cookie cutter to cut out donuts, and use a 1-inch round cookie cutter to cut out the centers to create donut holes.
Gather the scraps of dough and knead them back into a ball. Cover and let them rest for 10 to 15 minutes before rolling out and cutting more donuts. It's important to let the dough relax for easier rolling.
Once you have your donuts cut out, gently reshape them if necessary and let them rest for another 10 to 15 minutes. This will allow them to puff up a bit more.
While the donuts are resting, heat the oil in a large, heavy-bottomed pot. Use a candy thermometer to monitor the temperature, heating the oil until it reaches 360 degrees Fahrenheit. Keep an eye on it, ensuring it stays between 350 to 375 degrees while frying.
Before frying, prepare your glaze by mixing together the powdered sugar and milk in a bowl until smooth. Set up a frying station with a cooling rack lined with paper towels beneath to catch any drips.
Once the oil is ready, gently lay 2 to 3 donuts into the hot oil at a time. Fry for about 2 minutes on each side, or until they’re golden brown. Use a spider or slotted spoon to carefully remove the donuts and place them on the cooling rack.
Finally, dip the warm donuts into the glaze. You can either dip just the tops or both sides, depending on your preference. Allow them to cool on the rack, letting the glaze set.