Preheat your oven to 375°F (190°C).

In a large mixing bowl, combine the all-purpose flour, granulated sugar, baking powder, salt, and ground cinnamon. Stir until well combined.

In a separate bowl, whisk together the milk, melted unsalted butter, and egg until smooth.

Gently pour the wet mixture into the dry ingredients, folding them together carefully.

Dust your work surface with flour and roll out the dough to about 1/2 inch thick. Cut out your donuts using a donut cutter.

Arrange the shaped donuts on a greased baking sheet, ensuring they have space to rise. Bake for 10-12 minutes.

Prepare the cinnamon sugar coating by mixing granulated sugar and ground cinnamon in a shallow dish.

As soon as the donuts are out of the oven, let them cool for a minute then roll them in the cinnamon sugar mixture.