Heat oven to 350 degrees. Add 12 muffin/cupcake liners to a muffin pan. Lightly coat with cooking spray. Set aside.
In a medium size bowl, whisk together flour, baking powder, salt and sugar.
In a small bowl, whisk together butter, egg, orange juice, sour cream and zest. Add wet mixture into dry and stir to blend. Do not over mix or muffins will be tough. Spoon into 12 muffins cups. Bake for 18 to 20 minutes until a tooth pick inserted into center of muffin comes out clean. Remove from oven and cool.
For glaze, mix together confectioners sugar, orange juice and zest. Drizzle over muffins. Let set and drizzle a second time if desired.