Chicken in Onion Cheese Sauce

"Let’s make a tasty warming dish for a family lunch. The chicken baked in onion sauce with hard cheese turns out incredibly juicy, gentle and fragrant. Appetizing pieces of meat with a large amount of gravy can be completed with gentle polenta, mashed potato or celery puree. Don’t forget to buy the crispy baguette for lunch. It’s very tasty to dip slices of fresh bread in fragrant dense sauce. Ingredients: chicken thigh 8 pcs; cheese 150 g; onion 4 pcs; garlic 4-5 clove; dijon mustard 2 tbsp; butter 30 g; water 400 ml; apple cider vinegar 1 tbsp; olive oil 50 ml; seasoning for chicken 0.5 tsp; rosemary 0.5 tsp; salt - to taste; black pepper - to taste."