Cook rice according to package instructions, or heat up a pre-cooked package of white or yellow rice.

Preheat the oven to 425 degrees Fahrenheit. Line a 13x18 sheet pan with parchment paper. Add the boneless, skinless chicken thighs to the pan. Around them, add the chopped squash or zucchini, onions, bell pepper, tomatoes, and kalamata olives.

In a separate bowl, add the olive oil, lemon juice, minced garlic, oregano, mustard, and salt & pepper. Whisk well, and pour the dressing over the chicken and vegetables.

Bake the chicken for 30-40 minutes, until browned. The chicken should reach an internal temperature of 165 degrees Fahrenheit, which you can check using a meat thermometer.

Remove chicken from oven and serve over rice. Add crumbled feta cheese to the top, and enjoy!