When I roast a chicken I put parsnips, carrots, onions, celery and mushrooms in the bottom of the pan with NO WATER.
When the chicken is roasted and the vegetables are nice and brown, you can add a little bit of water or chicken broth to the bottom of the pan.
It should look like this when you take it out of the oven.
Take all the delicious roasted vegetables out leaving the drippings in the pan. Put vegetables in a blender, add chicken broth and blend it up!
Now use the pureed vegetables to thicken your gravy. Add some chicken bouillon, chicken broth, salt, pepper and thyme.
You may need to add a tiny bit of flour/butter to thicken at the end. Then add a few pats of butter.
This makes a TON of gravy. You can freeze it and use it later. :) Mmm!