01 - In a large bowl, whisk together flour, sugar, baking powder, salt, and cinnamon until evenly combined.
02 - In a separate bowl, whisk together milk, eggs, melted butter, and vanilla extract until well blended.
03 - Add the wet ingredient mixture to the dry ingredients and fold together until just combined, avoiding overmixing.
04 - Heat 2 inches of vegetable oil in a deep saucepan to 350°F over medium-high heat.
05 - Using a small cookie scoop or two spoons, carefully drop tablespoon-sized portions of batter into the hot oil. Fry in batches, turning occasionally, until golden brown throughout, approximately 2 to 3 minutes per batch.
06 - Remove fried donut holes with a slotted spoon and transfer to a paper towel-lined plate to drain excess oil.
07 - While the donut holes are still warm, roll them in the cinnamon sugar mixture until evenly coated on all sides.
08 - Place chopped chocolate and butter in a heatproof bowl. Heat cream in a small saucepan until simmering, then pour over the chocolate and butter. Allow to rest for 1 minute, then stir until smooth and glossy.
09 - Arrange warm cinnamon sugar-coated donut holes on a serving plate and serve with the warm chocolate dipping sauce.