In a large bowl, whisk together the flour, sugar, baking powder, salt, and cinnamon until well combined.
In another bowl, mix the milk, egg, melted butter, and vanilla extract until smooth.
Gradually add the wet ingredients to the dry ingredients, stirring until just combined. Be careful not to overmix; it’s okay if there are a few lumps.
Heat oil in a deep pot or deep fryer over medium heat. You want enough oil to fully submerge the donut holes, about 2-3 inches deep.
Once the oil is hot (about 350°F or 175°C), use a small cookie scoop or your hands to form small balls of dough (about 1 inch in diameter) and carefully drop them into the hot oil, a few at a time.
Fry the donut holes for about 3-4 minutes or until they are golden brown, turning them occasionally to ensure even cooking.
Remove them from the oil and place them on a paper towel-lined plate to drain excess oil.
In a separate bowl, whisk together the maple syrup and powdered sugar until smooth to create the glaze.
While the donut holes are still warm, dip each one in the maple glaze, ensuring they are fully coated.
Place the glazed donut holes on a wire rack to allow the glaze to set for a few minutes.
Notes
Ensure the oil is at the right temperature for even cooking.