Adjust racks to top and middle positions and preheat oven to 425 degrees. Cut potatoes into ¼-inch-thick wedges. Peel and mince garlic. Halve, peel, and mince half the onion (whole onion for 4 servings). Roughly chop parsley. Cut broccoli florets.

Toss potatoes on a baking sheet with a drizzle of oil, salt, and pepper. Roast on top rack until browned and tender, 20-25 minutes.

Meanwhile, in a large bowl, combine beef, garlic, panko, half the minced onion, and a pinch of salt and pepper. Gently combine into two 1-inch-tall loaves (four loaves for 4 servings) and place on a second baking sheet.

Brush tops of meatloaves with half the ketchup (all for 4).

Toss broccoli on opposite side of sheet from meatloaves with a drizzle of oil, salt, and pepper. Roast on middle rack until broccoli is cooked through, 15-20 minutes. TIP: If broccoli finishes first, remove from sheet and continue roasting meatloaves.

Meanwhile, melt 1 TBSP butter (2 TBSP for 4 servings) in a medium pan over medium heat. Add remaining minced onion, stirring until softened, 3-4 minutes.

Sprinkle with flour, stir vigorously to combine. Whisk in stock concentrate and ½ cup water (1 cup for 4). Bring to a simmer and cook until thickened and saucy, 3-4 minutes.

Stir in remaining parsley; season with salt and pepper.

Slice meatloaves crosswise. Divide meatloaves, potato wedges, and broccoli between plates. Spoon gravy over meatloaves and serve.