Preheat oven to 400 degrees F. Meanwhile, in a small bowl, stir together butter, maple syrup, and chopped thyme. Set aside.
Place chicken in a roasting pan and stuff cavity with lemon and all but 4 thyme sprigs. Slide hands under the chicken's skin to loosen. Spread half of reserved butter mixture between loosened skin and meat. Rub remaining butter mixture on top of skin and season with salt and pepper.
Roast chicken until an instant-read thermometer inserted into thickest part of thigh reaches 165 degrees F, about 1 1/2 hours. Remove chicken from oven and let rest for 10 to 15 minutes before carving. Garnish with remaining thyme sprigs.