In large skillet on medium, heat olive oil to medium high. Pat chicken breasts dry and season with salt and pepper. Place in skillet and cook for 4 to 5 minutes on each side, or until outside is nicely browned and lifts easily from pan. Remove chicken from pan, reduce heat to low, and add thyme sprigs and onion. Stir frequently and cook for 3 to 5 minutes until, onions are soft and translucent. Increase heat to medium and deglaze pan by adding lemon juice and scraping up brown bits from pan surface with a wooden spoon. Add chicken broth and continue until bottom of pan is “clean.”

Add chicken back into pan and top with spinach; cover and let stand for 2 minutes, or until spinach has wilted. Remove lid from pan and stir spinach to incorporate evenly through the mixture. Add artichoke heart pieces evenly in pan. Cook, uncovered, for about 2 to 3 minutes, until sauce is reduced slightly. Add yogurt and whisk it into the sauce until smooth. Using tongs, lift chicken breasts and place them on top of the spinach and other ingredients. Remove from heat and garnish with lemon zest and fresh thyme leaves.

To serve, place a chicken breast on each of 2 plates and top with spinach, artichokes, and sauce.