Spicy Sausage Bread

Name: Spicy Sausage Bread
Ingredients: 1 pound pizza dough; 1 small shallot; 4 ounces baby bella or cremini mushrooms; 2 cloves garlic; 3 tablespoons olive oil, divided; 2 teaspoons Italian seasoning; 1 to 2 teaspoons red pepper flakes; 1 teaspoon kosher salt; 1 teaspoon freshly ground black pepper; 1 pound uncooked sweet or spicy Italian sausage, casings removed if needed; All-purpose flour, for stretching out the dough; 2 cups shredded Italian cheese blend (4 ounces); 1 large egg; 1 tablespoon grated Parmesan cheese (optional); Marinara sauce, for serving