What you need:
For the donuts:
1 cup (125g) all-purpose flour (spoon & leveled)
1 teaspoon baking powder
1/4 teaspoon baking soda
1/2 teaspoon salt
1/2 teaspoon ground cinnamon
1/4 teaspoon ground nutmeg
1 large egg, at room temperature
1/3 cup (65g) packed light brown sugar
1/4 cup (60ml) milk1
1/4 cup (60g) yogurt2
2 Tablespoons (30g) unsalted butter, melted
1 and 1/2 teaspoons pure vanilla extract
For the topping:
1 cup (200g) granulated sugar3
1 teaspoon ground cinnamon
1/2 cup (115g) unsalted butter, melted
What to do:
1. Preheat oven to 350°F (177°C). Spray a donut pan with non-stick spray. Set aside.
2. Make the donuts: Whisk the flour, baking powder, baking soda, salt, cinnamon, and nutmeg together in a medium bowl. Set aside. Whisk the egg, brown sugar, milk, and yogurt together until smooth. Add the melted butter and vanilla, whisking until fully combined.
Pour the wet ingredients into the dry ingredients and mix until just combined. Do not overmix. The batter will be very thick.
4. Spoon the batter into the donut cavities. (I used a piping bag and put the bag in a cup to keep it stable while I spooned the batter in. You can also fill the batter in a zip-lock bag.) Then pipe the batter into each donut cup, filling 2 ∕ 3 –3 ∕ 4 of the way full
5. Bake for 9–10 minutes or until the edges are lightly browned. Allow to cool for about two minutes and transfer to a wire rack set on a large piece of parchment paper or on a large baking sheet. Bake the remaining donut batter (there is usually enough batter for 1-2 more donuts) and once baked, transfer to the wire rack. Allow donuts to cool down until you can handle them.
6. Top the donuts: Combine the sugar and cinnamon in a medium bowl. Dip the donuts in the melted butter, then dunk into the cinnamon sugar mixture coating all sides.
Donuts are best served immediately. Leftovers keep well covered tightly at room temperature for up to 2 days.
Recipe from: Sally's Baking Addiction