Combine the mustard, olive oil, garlic , herbs, and agave in a small bowl.
Note: I used equal amounts of dried sage, rosemary, and thyme for the herbs. If you use fresh, double the amount.
Line a large sheet pan with foil and spray lightly with cooking spray. Heat oven to 425 degrees.
Lay the chicken thighs bone side down on the pan. Spread the mustard mixture evenly on the tops of each thigh. Toss the sweet potato and red onion with 1/2 tablespoon of olive oil. Season with salt, pepper and garlic powder to taste. Nestle these around the chicken thighs.
Roast for 20 minutes.
Toss the broccoli with the remaining olive oil and season to taste with salt, pepper, and garlic powder. Add to the sheet pan, placing them evenly around the rest of the ingredients.
Roast another 20 minutes or so until the chicken is cooked through and the vegetables are tender. Divide between two plates and serve.