In a large bowl beat ricotta cheese with an electric mixer on medium speed until smooth. Add eggs and vanilla; beat until combined. Add flour, granulated sugar, baking powder, and salt. Beat on low speed until just combined. Let batter stand for 30 minutes. Drop batter by well-rounded teaspoonfuls, four or five at a time, into deep hot fat (365 degree F). Cook 2-1/2 to 3 minutes or until golden brown, turning once. Remove doughnuts with slotted spoon and drain on paper towels. Repeat with remaining batter. Cool completely. Shake doughnuts in a bag with powdered sugar, granulated sugar, or cinnamon/sugar mixture. Makes 3 dozen.