Heat oil in a large dutch oven to 375 degrees F. I use a meat thermometer to gauge temperature. Alternatively, add a small piece of food to hot oil and if it immediately sizzles and rises to the surface of the oil, it should be ready.In a medium bowl, combine flour, sugar, baking powder, cinnamon, and salt. Whisk to combine. Pour melted butter over dry ingredients. Mix until crumbly. Stir in milk and egg until a thick batter of dough forms.Take 1 1/2 -2 tablespoons of dough and form into a small ball. Repeat until dough is gone. Carefully drop in 5-6 donut holes into hold oil. Fry, turning once, for three minutes or until golden. Place the fried holes on a cookie sheet set above a plate and allow the oil to drain off.Toss 1 cup sugar in a paper lunch bag. Close bag and shake donut holes in batches of 6 until coated.We love to eat these warm or to rewarm them in a skillet on low. Store in air-tight container until ready to eat.