In a medium bowl, dissolve the yeast and sugar in warm water. Let stand for about 10 minutes.

Add the flour, oil and salt to the mixture and mix until well combined and smooth. Let rest while you make the sausage filling.

In a medium skillet, cook the sausage and onion together until the sausage is no longer pink. Drain off any excess grease and let the sausage cool.

In a medium bowl, mix the ricotta, mozzarella and Parmesan together. Add the cooled sausage mixture to the cheese and mix together. 

Divide the pizza dough into 8 equal parts. Roll each part into a 6" circle and then place some of the pasta sauce in the middle of the circle, being careful not to get it within a half-inch of the edge of the dough.

Scoop about 1/8 cup of the cheese/sausage mixture and place on top of the sauce. Fold the dough in half to make a semi-circle shape and press the edges of the dough together. Use the tines of a fork to press the edges together all the way around the rounded edge of the calzone. Repeat with all of the dough.