Stuffed Chicken with Roasted Root Vegetables

Name: Stuffed Chicken with Roasted Root Vegetables
Ingredients: ½ stick unsalted butter, softened; ½ medium-sized onion, diced; grated zest of 1 lemon; 2 tbsp freshly chopped sage, parsley, thyme or rosemary; 4 cups soft white breadcrumbs; 1 large good-quality roasting chicken (4 to 5 lbs); salt and pepper; ½ lemon; 8 small carrots, halved lengthwise; 2 small parsnips, halved and cut into wedges; 12 large shallots, peeled and trimmed; 1 small butternut squash, peeled, seeded and cut into wedges; ¼ cup olive oil, or more as needed; 1 tsp fresh thyme leaves; salt and black pepper