In a medium bowl, whisk together 1 tablespoon olive oil, 2 cloves minced garlic, lemon juice, oregano, salt, and pepper.
Add the cubed chicken to the marinade, toss to coat, and refrigerate for 20 minutes.
Prepare the tzatziki by combining the Greek yogurt, grated cucumber (squeezed to remove excess moisture), 1 clove minced garlic, and dried dill in a small bowl; set aside.
Heat the remaining 1 tablespoon olive oil in a large skillet over medium-high heat.
Add the chicken and cook for 6 to 8 minutes, stirring occasionally, until the internal temperature reaches 165°F (74°C).
Assemble the bowls by layering 1/2 cup of cooked quinoa in each of the four bowls.
Divide the cooked chicken, diced cucumber, cherry tomatoes, red onion, and Kalamata olives evenly among the bowls.
Top each bowl with a dollop of tzatziki, a sprinkle of feta cheese, and fresh parsley.