In a large bowl, cream butter with the 2 different kinds of sugar with an Electric hand mixer for a few minutes until fluffy, mix in the eggs, and finally the yogurt.
Sift dry ingredients together (flour, baking powder, salt, cinnamon) then fold into the wet ingredients by hand using a Rubber spatula). Do not use a mixer at this point.
Pipe or spoon the donut batter into the cavities of your donut mold.
Bake for 13-15 min or until a skewer inserted comes out clean.
Cinnamon sugar coating
Mix granulated sugar with the cinnamon.
Melt a small amount of butter and apply lightly but thoroughly all around the donuts then dump them in the cinnamon sugar mixture.
Serve the donuts fresh. Any leftovers can be stored at room temperature in an air-tight container for 2-3 days.
Notes
INGREDIENT NOTES
All ingredients must be at room temperature to properly emulsify: eggs, butter, yogurt, etc.
TECHNIQUE NOTES
A digital scale is required for a consistent, happy baking experience:)
Do not overwork the cake batter, after the wet ingredients are whipped up, switch to a rubber spatula to incorporate the dry ingredients
If not using a silicone baking mold, make sure to properly grease your tin. Check my article about how to get cake out of the mold and how to properly prepare a non-silicone mold
Always pre-heat your oven and consider using a digital oven thermometer for the best results
Baking these cinnamon sugar donuts takes 15 minutes in my oven however focus on the texture, not the time. Apply the toothpick check (it should come out clean) to avoid raw donuts, however, do not overbake them as that would result in a dry texture.
When applying the melted butter, make sure to apply only a small amount, however, thoroughly, all around the donuts. The cinnamon sugar will only stick to the part that is buttered.