Preheat oven to 350F/180C.
In a nonstick skillet heat butter over medium heat. Add celery and onion and cook until softened. Remove from heat and add bread, chicken stock, poultry seasoning, salt and pepper. Mix and set aside to cool.
Combine beef, eggs, carrot, zucchini, mustard, ketchup, breadcrumbs, salt and pepper. Divide mixture in half. Add mushrooms to one half of mixture.
Spray muffin pan with vegetable spray. Place 2 tbsp of mixture in six muffin cups. Divide stuffing and place on top; cover with remaining meat mixtures.
Bake for 25 to 30 minutes. Top Kids’ meatloaves with potato and decorate with vegetables.