Preheat the oven to 350 degrees F (175 degrees C). Lightly coat a baking dish with cooking spray.

Heat oil in a sauté pan over medium-high heat. Add carrots, onions, and celery; sauté until onions translucent, 5 to 7 minutes.

Meanwhile, heat a large skillet over medium-high heat. Add ground beef; cook and stir until browned and crumbly, 5 to 7 minutes. Drain; discard grease.

Move beef to one side of skillet; add butter and melt over medium heat. Whisk in flour, a little at a time until combined. Whisk in beef broth. Add sautéed vegetables, garlic salt, onion powder, garlic powder, and black pepper. Bring to a boil; cover and remove from heat.

Meanwhile, add baking mix to a bowl; stir in buttermilk until a soft dough forms. Transfer dough to a piece of waxed paper; roll to 1/2-inch thickness. Cut out biscuits with a 2 1/2-inch round biscuit cutter dipped in baking mix.

Pour beef mixture into prepared baking dish; top with biscuits.

Bake in the preheated oven until biscuits browned, 24 to 25 minutes.