Nutella Glazed Baked Donuts

Name: Nutella Glazed Baked Donuts
Ingredients: 1 cup all purpose flour; 1 tsp. baking powder; 1/4 tsp. baking soda; 1/4 tsp. ground nutmeg; 1/4 tsp. salt; 1 large egg, at room temperature; 1/3 cup light brown sugar; 1/4 cup milk, at room temperature (any kind works); 1/4 cup plain yogurt or sour cream, at room temperature; 2 tbsp. unsalted butter, melted; 1 1/2 tsp. vanilla extract; 1 cup confectioners sugar; 2 1/2 tbsp. nutella; 4-6 tsp. milk (any kind); 1/2 tsp. vanilla extract; sprinkles (optional)