Roast the chicken in the oven for about 1 hour and 15 minutes, as follows:<br >
<strong>At 15 minutes</strong> Brush the chicken with the remaining 1/2 tablespoon of butter. Scatter the sliced onion and carrot all around. Reduce the oven temperature to 350°.<br>
<strong>At 45 minutes</strong> Brush the lemon juice over the chicken. If necessary, add 1/2 cup of water to the vegetables to prevent burning.<br>
<strong>At 60 minutes</strong> Baste with the pan juices. Test for doneness: The drumsticks should move easily in their sockets; their flesh should feel somewhat soft. If not, continue roasting, basting and testing every 7 to 8 minutes, until an instant-read thermometer registers 165°.