Preheat oven to 425°. Toss the potatoes with 1T olive oil, the cumin seeds, 3/4 tsp salt, and pepper to taste. Spread on a large baking pan and roast for 25-30 minutes (beginning to brown).

Heat remaining 2T olive oil in a small skillet over medium heat. Add the garlic and cook until lightly golden, about 2 minutes. Remove from the heat and stir in the brown sugar, lemon juice and red pepper flakes. Remove the pan from the oven, push the potatoes to the sides and arrange the chicken breasts in the middle. Season the chicken with salt and drizzle with the garlic mixture. Return to the oven and bake until chicken is cooked through and potatoes are tender, about 20 minutes.

Remove from the oven; transfer the chicken to a cutting board and slice. Add the cilantro to the baking dish and toss with the potatoes. Drizzle with the pan juices and serve all together.