• Rinse the chicken breasts under cold running water and remove any excess fat. Drain well, then pat dry with paper towels.
• Cover the chicken with plastic wrap and gently pound with a meat tenderizer or a rolling pin until about 2 cm thick (3/4 inch).
• You can season the chicken breasts several hours ahead of time and let them marinate in the refrigerator so they fully absorb the spices.
• If seasoning just before cooking, start by preheating the oven to 220°C (425°F).
• In a dish, mix the olive oil with the spices, herbs, and salt. You can use a freezer bag if you prefer less cleanup. Add the chicken breasts and coat them well on all sides.
• Grease a baking sheet and place the chicken breasts on it. Add the rosemary sprigs and a few pink peppercorns.
• Bake on the middle rack for about 20 minutes. Ten minutes before the end of cooking, turn on the broiler and lightly brown the chicken to avoid drying it out.
• When the chicken comes out of the oven, cover the baking sheet with aluminum foil to trap the steam. This will help the chicken breasts stay tender and juicy.

Make the Creamy Mushroom Sauce

• Once the chicken breasts are in the oven, start preparing the sauce.
• Wash the mushrooms, remove the stems, and rinse them in plenty of water.
• Pat them dry and slice them. You can also buy pre-sliced mushrooms. I used frozen mushrooms.
• Heat a little olive oil in a skillet and sweat a chopped onion over low heat.
• When the onion becomes translucent, add the mushrooms.
• Sauté until the mushrooms are cooked, then add the cream, cheese, a bit of chives, and dried dill. Stir and let simmer until the sauce is thick and creamy.
• Add the cream after the chicken breasts are out of the oven. If the chicken is still baking, turn off the heat under the mushrooms and wait until the meat is ready.
• Serve the chicken breasts topped with the creamy mushroom sauce.
• Serve hot, accompanied by a fresh salad.