Sausage and Gravy Pie with Biscuit Crust

Name: Sausage and Gravy Pie with Biscuit Crust
Ingredients: 1 tablespoon unsalted butter, plus extra for buttering the pie plate; 4 pieces prepared biscuit dough (about 8 ounces); 8 ounces breakfast sausage, casings removed; 1 cup half-and-half; 1 large whole egg plus 1 large egg yolk; 1 scallion, sliced; Kosher salt and freshly ground black pepper; 2 ounces white Cheddar or Monterey Jack cheese, grated (about 1/2 cup)