Preparation Melt 3 tablespoons butter in heavy small skillet over medium-high heat. Add onion and sauté until light brown, about 7 minutes. Remove from heat; cool. Mix veal, breadcrumbs, eggs, 1/4 cup milk, salt, pepper, nutmeg and sautéed onion in large bowl until well blended. Form mixture into 24 meatballs (about 3 tablespoons of veal mixture in each). Heat oil in large nonstick skillet over medium-high heat. Working in batches, add meatballs to skillet and cook until brown on all side, turning often, about 8 minutes. Using slotted spoon, transfer meatballs to paper towels to drain. Cook carrots in pot of boiling salted water until almost tender, about 6 minutes. Drain; rinse under cold water. Drain thoroughly. Melt 4 tablespoons butter in heavy large Dutch oven over medium-low heat. Add flour; stir 3 minutes (do not brown). Gradually whisk in 2 cups milk and broth. Bring to simmer, whisking constantly. Simmer until mixture is thick and smooth, whisking often, about 8 minutes. Whisk in cream and mustard. Bring to simmer. Season with salt and pepper. Add meatballs and carrots. Cover; simmer until meatballs are just cooked through, about 5 minutes. Remove from heat. (Can be made 1 day ahead. Cover and chill. Rewarm over medium heat). Stir in chopped dill; cover and let stand 1 minute. Transfer to bowl. Garnish with dill sprigs and serve.
Preparation Melt 3 tablespoons butter in heavy small skillet over medium-high heat. Add onion and sauté until light brown, about 7 minutes. Remove from heat; cool. Mix veal, breadcrumbs, eggs, 1/4 cup milk, salt, pepper, nutmeg and sautéed onion in large bowl until well blended. Form mixture into 24 meatballs (about 3 tablespoons of veal mixture in each). Heat oil in large nonstick skillet over medium-high heat. Working in batches, add meatballs to skillet and cook until brown on all side, turning often, about 8 minutes. Using slotted spoon, transfer meatballs to paper towels to drain. Cook carrots in pot of boiling salted water until almost tender, about 6 minutes. Drain; rinse under cold water. Drain thoroughly. Melt 4 tablespoons butter in heavy large Dutch oven over medium-low heat. Add flour; stir 3 minutes (do not brown). Gradually whisk in 2 cups milk and broth. Bring to simmer, whisking constantly. Simmer until mixture is thick and smooth, whisking often, about 8 minutes. Whisk in cream and mustard. Bring to simmer. Season with salt and pepper. Add meatballs and carrots. Cover; simmer until meatballs are just cooked through, about 5 minutes. Remove from heat. (Can be made 1 day ahead. Cover and chill. Rewarm over medium heat). Stir in chopped dill; cover and let stand 1 minute. Transfer to bowl. Garnish with dill sprigs and serve.