Jojo’s Biscuits

Name: Jojo’s Biscuits
Cuisine: American
Ingredients: 4 cups self-rising flour, plus more for the work surface; 2 tablespoons baking powder; 1 teaspoon baking soda; 3/4 pound (3 sticks) salted butter, cold, cut into 1/2-inch pieces or grated; 2 large eggs, beaten, plus 1 large egg for brushing; 1 1/2 cups buttermilk, or as needed, plus 1 tablespoon for brushing; Strawberry Jam or Classic Sausage Gravy, for serving (optional, recipe follows); 1 1/2 to 2 pounds pork sausage; 6 tablespoons unsalted butter; 6 tablespoons all-purpose flour; 2 cups whole milk; Kosher salt and freshly ground black pepper