Preheat oven to 375 degrees. Thoroughly rinse produce and pat dry. Trim bottoms from Brussels sprouts and cut in half. Halve grape tomatoes. Lightly crush garlic with the flat side of a knife. Slice half of the lemon into eight thin rounds. Peel, halve, and cut onion into strips. Rinse chicken and pat dry.

In a medium oven-safe pan, heat 1 tsp. of olive oil over medium-high heat until nearly smoking. Season the chicken breasts with a pinch of salt and pepper and sear skin-side down for 4-5 minutes. Turn chicken to sear on second side and cook for 3-4 more minutes. When all sides are sufficiently browned, transfer chicken to a plate and set aside. Drain oil from pan and return to stove over medium heat.

Add 1 tsp. of olive oil to the pan in which you seared the chicken. Add onions and stir. As onions soften and release their juices, they will "clean" the browned bits from the pan. When onions are nearly translucent, add Brussels sprouts, tomatoes, crushed garlic, and half of the thyme sprigs. Cook for 3-4 minutes, stirring often.

Add white wine and cook for 30 seconds. Add chicken base and 1 cup of water to pan. Add drained artichoke hearts and chicken breasts. Squeeze the lemon half (to taste) into pan, then drop lemon in pan. Shingle sliced lemon on top of each chicken breast. Place in oven and cook 18-20 minutes, or until internal temperature reaches 165 degrees.

Discard lemon half and cooked thyme sprigs. Remove lemon rounds from chicken and arrange on side of bowl. Divide vegetables between two shallow bowls and ladle in some of the liquid from the pan. Serve chicken breasts over the top, skin side up, and garnish with a thyme sprig each.