Season the chicken breasts with salt and pepper. Heat olive oil in a large pan and brown the chicken on both sides. Set aside.
1 tbsp olive oil, 750-900 g boneless chicken breasts, Salt to taste
In the same pan, melt butter and sauté sliced onions, mushrooms, and garlic with a pinch of salt for 10 minutes.
1 medium onion, 250 g mushrooms, 2 garlic, 1 tbsp butter
Add the white wine and let it simmer for a couple of minutes. Then add the thyme leaves, bay leaves, tomato paste, diced tomatoes, and chicken stock.
125 ml dry white wine, 4 fresh thyme sprigs, 2 fresh bay leaves, 1 tbsp tomato paste, 150 g canned diced tomatoes/crushed tomatoes, 350 ml chicken stock
Bring the chicken breasts back to the pan, cover, and simmer for 20 minutes. Uncover and cook for an additional 10 minutes.
750-900 g boneless chicken breasts
If the sauce is too watery by the end of the cooking time, simmer uncovered to reduce it.
Remove the chicken from the pan and keep it warm. Boil down the sauce until it is syrupy and concentrated in flavor.
Return the chicken to the sauce and serve.