Simple Roasted Grape Chicken

Name: Simple Roasted Grape Chicken
Ingredients: 1/2 pound organic red seedless grapes; 2 chicken legs; 1 teaspoon minced garlic; 1 sprig fresh rosemary (about 4”), cut in half; 1 1/2 tablespoon olive oil; 1 tablespoon red wine vinegar; 1/2 teaspoon kosher salt; black pepper; washed and dried frisée, for serving (optional); 1 tablespoon minced shallot or onion; 1/4 cup vermouth; 1/4 cup chicken stock; 1 tablespoon unsalted butter, cut into small cubes (room temperature); 2 tablespoons minced Italian parsley; Salt; splashes Lemon