I love flavouring the chicken with grainy mustard but if you don't have any, you can use regular dijon. If you don't have either, omit it. It will still be delicious.
Preheat oven to 425 degrees. Pat chicken dry. In a small bowl, mix the grainy mustard with 1 tablespoon olive oil and rub the mixture all over the chicken pieces. Season chicken generously with salt and freshly ground black pepper.
Heat the remaining tablespoon of olive oil in an ovenproof 12-inch heavy skillet (preferably cast-iron) and sautée shallots until slightly caramelized and softened, about 5 minutes.
Add the wine and chicken broth. Place the chicken pieces in the pan, skin side up. Top with thyme sprigs. Roast the chicken for about 15 - 20 minutes. Add the grapes to the pan and quickly baste the chicken pieces. Roast for 15 - 20 more minutes, until the grapes seem slightly blistered and cooked down.
Serve immediately with crusty bread, or desired side.
Notes
*In order to avoid an excessively fatty sauce, I like to trim as much fat off the chicken pieces as possible, leaving only the top skin intact. Kitchen shears work well for this job. **Avoid green grapes which will not get as sweet as the red varieties when roasted