Add in the flour and stir just until smooth again.
1 & 3/4 cups minus 2 tbp (8oz) all-purpose flour
Using a large muffin scoop or 1/4 cup measuring cup, fill the wells of the prepared baking pans about 3/4 full.
Bake for about 15 minutes or until a toothpick inserted into the center comes out clean. Let cool enough to handle.
Toss the sugar and cinnamon in a medium ziplock bag. While the donuts are still warm, gently shake them in the sugar mixture to coat. Place them on a wire rack to cool or enjoy warm. See notes.
1/2 cup (100g) granulated sugar, 2 tsp ground cinnamon
Notes
Because these donuts are quite moist, it's best to coat them just before serving or at most a couple of hours before.
Store leftover donuts at room temperature on a cooling rack. Cover the donuts with a large tupperware container or sheet of wax paper. You want to shelter them, yet still allowing for air circulation.