Preheat your oven to 350°F (177°C) and grease a donut pan thoroughly with nonstick spray.
In a large mixing bowl, whisk together flour, baking powder, baking soda, salt, and nutmeg.
In a separate medium bowl, combine egg, brown sugar, milk, and sour cream until smooth.
Whisk the melted butter and vanilla extract into the liquid mixture.
Pour wet ingredients into the dry ingredients and stir just until no streaks of flour remain.
Transfer batter into a zip-top bag and snip the corner to create a piping bag.
Pipe batter into donut cavities, filling each no more than two-thirds full.
Bake for 9 to 10 minutes or until a toothpick comes out clean.
Cool in the pan for 5 minutes before transferring to a wire rack.
Melt chocolate chips to create the glaze and dip the cooled donuts into the chocolate.