Garnish: ground black pepper, chopped fresh parsley
Instructions
In 12-inch cast-iron skillet, heat 1 tablespoon oil over medium-high heat. Add minced onion and carrot; cook, stirring occasionally, until tender, 4 to 5 minutes. Remove from heat.
In a large bowl, combine bread crumbs and milk; let stand for 10 minutes. Stir in onion mixture, ketchup, eggs, parsley, salt, and pepper. Gently stir in beef until well combined. Scoop mixture by 2 tablespoons, and roll into balls.
In same skillet, heat 2 tablespoons oil over medium heat. Add mushrooms; cook, stirring occasionally, until browned and any liquid has evaporated. Remove mushrooms using a slotted spoon. Add sliced onion; cook, stirring occasionally, until lightly browned, 7 to 8 minutes. Remove onion from skillet.
In same skillet, heat remaining 3 tablespoons oil over medium heat. Add meatballs; cook, turning occasionally, until browned all over, about 8 minutes. Remove meatballs from skillet.
Melt butter in skillet over medium heat. Whisk in flour until smooth; cook, whisking constantly, for 1 minute. Gradually whisk in broth, scraping browned bits from bottom of skillet. Cook, whisking occasionally, until mixture is thickened, about 5 minutes.
Whisk in cream until combined. Stir in meatballs, mushrooms, and onion; cook, stirring occasionally, until sauce is thickened and meatballs are cooked through, 10 to 15 minutes. Serve with mashed potatoes. Garnish with pepper and parsley, if desired.
Recipe by Southern Cast Iron at https://southerncastiron.com/meat-loaf-meatballs-mushroom-gravy/