Preheat your oven to 375°F (190°C).

In the cast iron skillet, heat 1 tablespoon of olive oil over medium-high heat. Add the chicken, salt, pepper, and garlic. Sauté for 6-8 minutes until cooked through.

Remove chicken, and in the same skillet, add diced onion and cook for 8-10 minutes. Deglaze with 2 tablespoons of white wine.

Return chicken to skillet, add remaining wine, chicken stock, sour cream, cream cheese, Gruyere cheese, and thyme. Combine well.

Spread the mixture in the skillet and sprinkle with remaining Gruyere cheese. Bake for 15-18 minutes until bubbly and golden brown.

Remove from oven, garnish with thyme and pepper, and serve warm with crusty bread or veggies.