• Preheat oven to 350°F. Spray a donut pan with non-stick spray. Set aside.

Make the Donuts:

• Whisk the flour, baking powder, baking soda and salt together in a medium bowl. Set aside.
  1 cup all-purpose flour, 1 teaspoon baking powder, ¼ teaspoon baking soda, 1 teaspoon kosher salt
• Whisk the egg, brown sugar, buttermilk, and sour cream together until smooth.
  1 large egg, at room temperature, ⅓ cup dark brown sugar, ¼ cup buttermilk, ¼ cup full-fat sour cream
• Add the melted butter and vanilla, whisking until fully combined.
  2 tablespoons unsalted butter, 1 ½ teaspoons vanilla extract
• Pour the wet ingredients into the dry ingredients and mix until just combined. Do not over mix. The batter will be very thick.
• Pipe the batter into the donut cavities—I highly recommend using a large zipped-top bag for ease.
• Cut a corner off the bottom of the bag and pipe the batter into each donut cavity, filling ⅔ – ¾ of the way full.
• Bake for 9–10 minutes or until the edges are lightly browned.
• Allow to cool for about two minutes and turn out onto a wire rack set on a large piece of parchment paper or on a 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.

Prepare the Glaze:

• Stir all ingredients together until smooth and well combined.
  4 cups powdered sugar, ¼ cup whole milk, 3 tablespoons light corn syrup, 2 tablespoons unsalted butter, 1 teaspoon vanilla extract, pinch of salt
• Dip donuts and place on a wire rack set over a baking tray to catch the excess glaze.
• Serve immediately.