In a medium bowl whisk together the flour, baking powder, baking soda, salt and ½ teaspoon cinnamon.

In another large bowl beat eggs together until foamy. Gradually add in ½ cup of sugar and fully combine. Next add sour cream and vanilla and stir to combine.

Add the dry ingredients into the wet ingredients and stir until just combined. The dough will be very soft. Pat the dough into a disk, wrap it in plastic wrap, and refrigerate for at least 2 hours or up to 2 days. The dough will never become firm but it will be workable when cold.

Working on a lightly floured surface, pat or roll the dough out ½ inch thick. Cut out your donuts with a well floured donut cutter into donut holes or circles.

Heat your oil in a large pot or in a deep fryer to 365 F Fry and fry a several donut holes or full donuts at a time until they are a deep golden brown on one side, and then flipping them over until the other side is cooked. Use tongs to remove them from the hot oil and drain them on a paper towel lined plate.

To make the cinnamon sugar, combine ½ cup of white sugar and 2 tablespoon of cinnamon, and mix together on a plate. Roll the warm donut holes in cinnamon sugar. These are best if served while still warm or within a few hours of frying.