Mix the flour, baking powder, sugar, eggs, ricotta, lemon zest, and vanilla in a bowl until smooth.
Heat the oil to 340°F/170°C in a wide pot.
Lightly oil a spring-loaded ice cream scoop. Drop scoops of batter directly into the hot oil.
Fry until deeply golden on both sides, 3 to 4 minutes total.
Transfer to a paper towel-lined plate. Dust with powdered sugar and serve warm with jam or chocolate spread.