In a large bowl, whisk together flour, sugar, baking powder, salt and cinnamon. Make a well in the center.: The air smells faintly of spice when you whisk these dry ingredients together, and you will notice a uniform pale tan color with tiny specks of cinnamon. This dry mix is the backbone, so sift any lumps away with your whisking motion to ensure even rise. Why this matters: even distribution of baking powder prevents pockets of uneven lift. Troubleshooting tip: if the mixture seems noticeably clumpy, quickly break lumps with the back of a spoon to avoid dense spots in the donuts.
In a large measuring glass, whisk together milk, egg, butter and vanilla extract. Pour into the center of the dry ingredients then mix with a large spoon. Stir until dough is combined but do not overmix. The dough will be sticky! Cover with plastic wrap and set the bowl in the fridge for 1 hour.: When you combine the wet mix you can smell warm vanilla and melted butter, which promise richness. The wet mixture should look homogenous and slightly glossy before you fold it into the dry bowl. Sensory cue: you will feel the batter change from powdery to tacky as you stir, and visually it will turn from dusty to cohesive. Why this matters: gentle mixing keeps the gluten development minimal, which preserves tenderness in the crumb. Troubleshooting tip: overmixing yields tough donuts, so stop as soon as no streaks of flour remain. Also chilling the dough firms it slightly, making rolling easier and helping preserve texture during frying.
After an hour, remove dough and place on a well floured surface. Roll dough out to be about 1/2-3/4 inch thick. Using a doughnut cutter, biscuit cutter or… something round, cut circles into the dough. To cut out the center, I used the wide bottom of a frosting tip, but you can also use a bottle cap or something of the sort.: The dough should feel pliable but not sticky after chilling, and when you press a finger it should slowly bounce back. As you roll, the surface will pick up a faint dusting of flour that prevents sticking, and you will see neat circular edges once cut. Why this matters: consistent thickness ensures even frying and uniform cook through. Troubleshooting tip: if the dough sticks while rolling, sprinkle a little more all purpose flour but avoid overflouring, which can dry the donuts out.
Heat oil in a large saucepan over medium heat so it’s about 2-3 inches deep. Once the oil hits 360-365 degrees, fry the doughnuts 2-3 at a time, for about 2 minutes per side, or until puffed and golden brown. Make sure you use a candy thermometer as this is the only way to determine the temperature! I have burned many doughnuts in my life. It is not pretty. Remove doughnuts with a slotted spoon and let cool on a paper towel. Repeat with remaining.: The oil will shimmer and faintly smell neutral when it reaches the right temperature, and the surface will show tiny ripples. As donuts hit the oil they should sizzle gently and begin to float, puffing as steam escapes. Why this matters: keeping oil at a steady temperature prevents overly greasy donuts or charred exteriors with raw centers. Troubleshooting tip: if the donuts brown too fast, your oil is too hot, so lower the heat and let it stabilize; if they soak up oil, the temperature is too low.
While doughnuts are cooling, heat a small saucepan over medium heat and add butter, vanilla, corn syrup and milk. Whisk to combine and once butter is melt, reduce heat to low and add chopped chocolate. Whisk ask to combine, then once smooth, remove from heat and stir in powdered sugar. Stir continuously until it is all dissolve and no lumps remain. Dunk each doughnut into the glaze, then cover with sprinkles. Let set for about 30 minutes.: When you fish the donuts out, listen for a soft hiss and notice the surface turn a warm golden brown that darkens slightly as they rest. Laying them on paper towel helps absorb excess oil without flattening the shape, and within a few minutes the donut will feel set to the touch. Why this matters: proper draining keeps the final texture light rather than greasy. Troubleshooting tip: avoid stacking hot donuts, as trapped steam will make them soggy.
While doughnuts are cooling, heat a small saucepan over medium heat and add butter, vanilla, corn syrup and milk. Whisk to combine and once butter is melt, reduce heat to low and add chopped chocolate.: As the butter melts with the milk you will hear a gentle bubbling and smell a rich, dairy aroma. Adding chocolate at low heat invites the chocolate to soften and melt into a glossy pool, and whisking helps emulsify the mixture. Why this matters: gentle heat prevents chocolate from seizing, which would make the glaze grainy. Troubleshooting tip: if your chocolate looks grainy, remove from heat and keep whisking, small amounts of warm milk can coax it smooth again.
Whisk ask to combine, then once smooth, remove from heat and stir in powdered sugar. Stir continuously until it is all dissolve and no lumps remain. Dunk each doughnut into the glaze, then cover with sprinkles. Let set for about 30 minutes.: The finished glaze should be shiny and thick enough to coat the back of a spoon, and when you dip a donut you will hear a soft scraping sound as excess glaze drips back. As it cools the glaze will firm slightly into a tender shell, and sprinkles add a festive crunch. Why this matters: the continuous stirring ensures a silky texture without sugar grit. Troubleshooting tip: if the glaze is too thin, add a little more powdered sugar ; if too thick, stir in a teaspoon of warm milk at a time until desired consistency is reached.