Preheat your oven to 375°F (190°C).
In a small bowl, mix together garlic powder, onion powder, dried thyme, salt, and pepper. Rub this spice mixture evenly over both sides of the chicken breasts.
Heat olive oil in a large oven-safe skillet over medium-high heat. Once hot, add the seasoned chicken breasts and sear for about 4-5 minutes on each side until golden brown.
Remove the skillet from heat and spread the Boursin cheese evenly over the top of each chicken breast.
Scatter the halved cherry tomatoes and fresh spinach around the chicken in the skillet. Drizzle balsamic vinegar over the vegetables.
Transfer the skillet to the preheated oven and bake for 20-25 minutes, or until the chicken is cooked through (internal temperature should reach 165°F).
Remove from the oven and let it rest for 5 minutes before serving. Garnish with fresh parsley.