Whisk together the dry ingredients: In a medium bowl, whisk together the flour, sugar, salt, and baking powder.
Whisk together the wet ingredients: In a large bowl, whisk together the milk, egg, and melted butter.
Combine the wet and dry ingredients: Pour the dry ingredients into the wet ingredients and whisk until smooth.
Heat the oil: Heat about 2-3 inches of vegetable oil in a deep frying pan over medium-high heat until it reaches 375°F.
Pipe the batter: Using a piping bag or a plastic bag with a corner cut off, pipe the batter into the hot oil in a circular motion, starting from the outside and working your way in.
Fry the funnel cakes: Fry the funnel cakes for 2-3 minutes on each side, or until they are golden brown and cooked through.
Drain and dust: Remove the funnel cakes from the oil and place them on a paper towel-lined plate to drain excess oil. Dust with powdered sugar, if desired.