While the crust bakes, place the ricotta, yogurt, eggs, sugar, tangerine zest and juice into the bowl of a food processor and process until smooth. Pour into the crust and smooth the top. Bake for 50 to 60 minutes, until the filling is set and jiggles only slightly in the center when gently shaken. Cool on a rack. For neat slices, refrigerate until cold. Cut into 16 squares.