Preheat oven to 375°F Heat olive oil in a large skillet over medium high heat. Add sausage and cook about 4-5 minutes, breaking up the sausage with a wooden spoon as you go along. Add mushrooms and continue cooking until sausage is done and no longer pink.
Meanwhile, in a large bowl, mix well the ricotta, mozzarella, and basil. Season with salt and black pepper. Set aside.
Roll out each biscuit onto a lightly floured work surface using a rolling pin. Roll/flatten until double in size (6"-7" in diameter).
When sausage mixture is done, drain well on paper towels, patting down well to remove as much grease/oil as you can. Add to cheese mixture. Blending well.
To the rolls, place about 2 heaping tablespoons of the mixture into the center, keeping away from the sides. Using a pastry brush, brush around HALF of the edges. DO NOT BRUSH ALL AROUND OR IT WILL NOT STICK TOGETHER.
Fold rolls in half over the filling (fold the un-brushed side onto the brushed side). Seal the edges by gently pressing the tines of a fork around the folded edge.
Place onto ungreased baking sheet (best to use parchment or a silpat underneath) Brush tops with remaining eggwash and sprinkle with parmesan cheese. Using the tip of a sharp knife, pierce hole in top of calzones to allow steam to escape.
Bake for approximately 20 minutes until golden brown. Let sit a few minutes before serving with marinara sauce.