Prepare hot roll mix according to package directions, allowing dough to rise once.
Cook and stir sausage and onions in oil in Dutch oven until brown, about 15 minutes; drain fat, Stir in remaining ingredients except cheese.
Heat oven to 400 degrees. Roll out 2/3 of the dough on a lightly floured board. Roll until about ½ inch thick. Fit into 2-quart deep un-greased casserole, allowing 1-inch overhang.
Pour meat mixture into unbaked shell; sprinkle with mozzarella cheese. Roll remaining dough to fit top; crimp edge to seal. Cover edge with aluminum foil to prevent over browning. Bake until crust is brown..about 20 minutes.