Preheat oven to 400 degrees. Spray a large sheet pan with nonstick spray.
Place on the sheet tray: potatoes and Brussels sprouts.
In a small measuring cup, combine 3 tablespoons olive oil, 1 teaspoon of the minced garlic, and lemon zest. Drizzle over the vegetables, tossing to coat well.
Place chicken breasts on top of the vegetables in the center of the sheet tray.
Combine the remaining 1 tablespoon olive oil, the remaining 1/2 teaspoon minced garlic, lemon juice, thyme, salt and black pepper evenly over the chicken breasts and vegetables.
Roast chicken breasts and vegetables in a pre-heated oven for 25 to 30 minutes, until the chicken is cooked and the vegetables are tender and golden brown. Let chicken rest for 2 to 3 minutes before slicing.
Recipe adapted from Perdue.com