For the pasta dough:
Mound flour on clean surface, make well in center.
Add eggs and egg yolk to well.
Gradually mix flour into eggs with fork until shaggy dough forms.
Knead for 10 minutes until smooth and elastic.
Wrap in plastic, rest for 30 minutes.
For the filling:
Mix all filling ingredients in bowl until well combined.
Cover and refrigerate until ready to use.
Assembly:
Divide dough into 4 portions.
Roll each portion very thin (almost transparent).
Cut into 3-inch circles.
Place 1 teaspoon filling in center of each circle.
Fold into half-moon, press out air.
Wrap around finger, pinch ends to seal.
Place on floured surface while working.
Cooking:
Bring large pot of salted water to boil.
Cook tortellini in batches for 3-5 minutes until they float.
Meanwhile, brown butter with sage in pan.
Toss cooked tortellini with sage butter.
Serve with extra Parmesan.