Wash and dry all produce. Adjust rack to upper position and preheat oven to 425 degrees. Peel carrots, then cut on a diagonal into 1/3-inch-thick coins; halve any large coins. Cut potatoes into 1-inch cubes. Halve and peel onion, then mince until you have 1/2 cup (use the rest as you like). Finely chop parsley.

Toss carrots on a baking sheet with a large drizzle of oil and a large pinch of salt and pepper. Roast in oven for 15 minutes (we’ll add more to the sheet then). Meanwhile, place potatoes in a medium pot with a large pinch of salt and enough water to cover by 1 inch. Bring to a boil and cook until tender, about 15 minutes. Drain and return to empty pot off heat.

Place bread and 3 TBSP milk in a medium bowl. Break up bread with your hands until pasty. Thoroughly mix in beef, 2 TBSP minced onion, half the parsley, 1/4 tsp nutmeg, 1/2 TBSP meatloaf mix, salt, and pepper (we sent more nutmeg and meatloaf mix; our chefs used 3/4 tsp kosher salt). Shape mixture into four 1-inch-tall loaves.

Heat a large drizzle of oil in a large pan over medium-high heat. Add meatloaves and cook until browned on surface but not yet cooked through, about 3 minutes per side. Once carrots have roasted about 15 minutes, remove sheet from oven and give carrots a toss. Add meatloaves to same sheet and place in oven. Bake until meatloaves are cooked through and carrots are tender, about 15 minutes more.

Melt 2 TBSP butter in same pan over medium heat. Add remaining minced onion. Cook, tossing, until soft, about 2 minutes. Add flour and cook, stirring, until pasty, about 1 minute. Slowly whisk in 1/2 cup water, followed by stock concentrates and 1/4 cup milk (save the rest for the potatoes). Bring to a simmer, then whisk until thickened, about 1 minute. Season with salt, pepper, and a pinch of nutmeg to taste. TIP: Add more water if too thick.

Place pot with potatoes over low heat. Add 1/2 cup milk and 2 TBSP butter. Mash until smooth. (TIP: Add more milk if stiff.) Season with salt and pepper. Divide potatoes and meatloaves between plates. Drizzle with gravy. Add carrots and jam to the side. Garnish with remaining parsley.