In a large mixing bowl, whisk together the flour, sugar, baking powder, salt, and ground cinnamon until well blended.
In a separate bowl, beat the eggs and then add the milk, vanilla extract, and melted butter. Mix until fully combined.
Pour the wet mixture into the dry ingredients and stir gently until just combined. Be careful not to overmix; a few lumps are perfectly fine.
Heat oil in a deep frying pot or large saucepan over medium-high heat until it reaches 350°F (175°C). You can test the oil by dropping a small bit of the batter into it; it should bubble and rise to the surface.
Using a spoon or a cookie scoop, carefully drop small dollops of batter (about 2 tablespoons each) into the hot oil, being sure not to overcrowd the pan. Fry until golden brown, about 2-3 minutes on each side.
Once fried, use a slotted spoon to remove the beignets and place them on a paper towel-lined plate to absorb excess oil.
Allow the beignets to cool slightly, then dust generously with powdered sugar before serving.
Notes
Serve warm with powdered sugar and dipping sauces.