Marinate the chicken: In a large bowl (or freezer bag), mix together just 1 tablespoons of the olive oil, honey, mustard, garlic, red pepper flakes, salt and pepper. Add in the chicken breasts to marinate overnight in the refrigerator.
Sear the chicken: Heat a large saute pan over medium-high heat. Swirl in 1 tablespoons of olive oil. When shimmering, add in the chicken breast, skin-side down. Cook for 3-4 minutes, until skin is nicely seared. Flip the chicken and cook the other side for 3 minutes. Transfer to plate and set aside to finish cooking later.
Cook the vegetables: In the same pan (there still should be some oil), on medium heat, add in the onion, carrot, swiss chard stems (not leaves), and the lemon zest. Use your spatula to scrape up the bits in the pan. Saute for 5-6 minutes, until the vegetables are softened.
Cook the quinoa: Pour in the chicken broth and stir in the quinoa. When simmering, cook for 5 minutes, uncovered. Turn the heat to low and lay the lemon slices in the pan. Lay the swiss chard leaves on top of the quinoa. Transfer the chicken breasts back to the pan, on top of the swiss chard leaves. Cover and cook for 10 minutes until the quinoa is cooked through. Let rest for 5 minutes to allow the quinoa to absorb the remaining liquid.