In a large pan, heat a drizzle of oil over medium heat. Add the sliced white mushrooms and sauté for about 5–7 minutes until they turn golden brown.

In the same pan, add the boneless skinless chicken thighs, season with salt and pepper, and cook for about 4–5 minutes per side.

Sprinkle the dry quinoa over the chicken and pour in enough water to cover the mixture. Bring to a gentle boil.

Cover the pan and let it simmer for approximately 15 minutes, or until the quinoa is fluffy.

While the quinoa simmers, whisk together Dijon mustard, maple syrup, and lemon juice in a small bowl.

After the quinoa is ready, uncover the pan and fold in the baby spinach leaves. Cook for an additional 2 minutes.

Gently fold the sautéed mushrooms back into the pan along with the prepared mustard sauce.

Plate the dish and garnish with fresh parsley and red pepper flakes.