Preheat oven to 425 degrees F.

Line a sheet pan (18 x 13 inch) with parchment paper or foil. Place in oven as it heats.

While oven is heating, season chicken breasts with a drizzle of olive oil, and a sprinkle of garlic powder, sea salt, and black pepper.

In a small bowl, whisk together 1 tablespoon each of stone ground mustard, Dijon mustard, and balsamic vinegar, and 2 tablespoons honey. Brush mixture on chicken breasts.

In a medium bowl, combine thinly sliced Brussels sprouts and halved cherry tomatoes (or other preferred vegetables) with 1 tablespoon olive oil.

Remove pan from oven.

Place chicken brushed side up, on one end of sheet pan and vegetables arranged on the other side of the sheet pan.

Sprinkle vegetables with salt and pepper.

Return sheet pan to oven.

Bake for 20 minutes, bring pan out of oven to sprinkle with chopped rosemary.

Vegetables can be removed at this point and kept warm if they are tender and cooked. Continue to roast chicken for an additional 10 to 20 minutes, or until a thermometer inserted in the thickest part of the chicken reads 165 degrees F.

For additional browning, broil just the chicken breasts without the vegetables under the broiler 3 to 5 minutes more. Garnish with chopped rosemary.