Preheat the oven to 425 degrees F. Lay a large rimmed 18x13 inch "half sheet" baking pan out and spray with nonstick cooking spray. Place the chicken thighs on the baking sheet.
Peel the onion, and cut into quarters. Then slice into 1/4 inch wedges. Seed the bell pepper, and slice into 1/4-inch strips. Then cut the strips in half. Peel the sweet potato, and cut into 1/4-inch rounds. Then cut all the rounds into quarters. Spread the vegetables out on the baking sheet in a single layer.
Sprinkle the top of the chicken and vegetables with curry powder, Chinese five spice, cayenne, thyme, 1 1/2 teaspoons salt, and black pepper to taste. Bake for 20 minutes.
Meanwhile, place the coconut milk, peeled garlic cloves, ginger, honey, and cornstarch in the blender. Puree until smooth.
After 20 minutes, remove the sheet pan from the oven. Pour the coconut mixture over the top of the chicken and veggies. Jiggle the pan a little to help mix the roasted spices into the coconut milk. Then place back in the oven for 10 minutes, or until the curry sauce simmers. Serve warm.
NOTES: This is a great low carb recipe as-is, However it tastes amazing over rice and can stretch to serve six people. Feel free to substitute other vegetables/ingredients such as green beans, zucchini, or chickpeas.