¼ cup unsalted butter, melted, divided
2 cups all-purpose baking mix (such as Biqsuick)
2 ounces sharp cheddar cheese, shredded (about ½ cup)
4 ¼ cups whole milk, divided
1 pound pork breakfast sausage
1/3 cup (about 1 ½ ounces) all-purpose flour
½ teaspoon kosher salt
½ teaspoon black pepper
1/8 teaspoon dried sage
Heat a camping stove to medium (about 350° to 450°F), or fit a grilling grate over the direct heat of the embers.
Grease a 9-inch round cake pan with 1 tablespoon of the melted butter. Combine the baking mix, cheese, ¾ cup of the milk, and 2 tablespoons of the melted butter in a medium bowl, stirring just until combined. Drop the dough by heaping tablespoonfuls into the greased cake pan. Place the pan on top of the foil balls in the preheated Dutch oven; cover with the lid. Bake until the biscuits are browned on bottom and done, 30 to 35 minutes.
Meanwhile, place a 12-inch cast-iron skillet over medium on a camping stove or on a grilling grate directly over the heat source. Add the sausage, and cook, stirring until the sausage crumbles and is no longer pink, 6 to 8 minutes. Stir in the remaining 1 tablespoon melted butter. Sprinkle the flour over the mixture; stir to combine, and cook 1 minute. Slowly stir in the remaining 3 ½ cups milk until combined. Cook, stirring often, until the mixture begins to thicken, 8 to 10 minutes. Stir in the salt, pepper, and sage. Serve the gravy over the biscuits.