Prepare a cookie sheet by covering it with parchment paper; have rice flour out for sprinkling
Take the rolled portion of pasta dough, and slice of the ends to make a rectangle; the slice in half or in thirds, depending upon the length of your dough
Using one portion of the dough, place it horizontally in front of you and tilt the pastry bag vertically and disperse a small mound of filling on the long edge of the pasta sheet closest to you; continue along the edge of the pasta sheet, just far enough a part to pinch between each mound with fingers
Once the pasta sheet is lined with mounds of filling, take a firm hold of each end of the sheet, and turn it over on top of itself, ensuring there is an edge formed one turned (see above photo)
Gently press the edge to seal the sheet together, and close one end of the pasta filled with the mounds
Using the pointer finger and thumb of both hands, pinch the dough around each mound of filling starting at the end that you have closed with a pinch
Move down the row of mounds, repinching the one pinched side and closing the open side with a new pinch until the entire row is pinched, then pinch the other end
Using a round pasta cutter (see photo) trim off the long sealed edge; turn the filled pasta sheet so that it is in front of you horizontally and the mounds are exactly upside down
Line up the pasta roller (as in the photos above), very close to the dough and then just quickly push it through to cut each piece of Agnolotti del Plin free from the line- up; continue until each portion of filling has become an Agnolotti del Plin
Dust with rice flour to avoid sticking and place on parchment covered pan until ready to cook, or freeze
Continue until all Agnolotti del Plin have been formed
At this point, you can cover with a towel until cooking time, or fast freeze over night and then portion into zip lock bags for serving another day