Lasagna without pre-cooking the sheets

Ingredients

• 30 ml Olive oil
• 1 piece Onion
• 2 clove(s) Garlic
• 450 g Ground beef
• 2 piece(s) Carrots
• 3 piece(s) Fresh tomatoes
• 1 stalk Celery
• 1 tsp Salt
• 1 tsp Black pepper
• 1 tsp Sweet paprika
• 1 tsp Herbes de Provence
• 400 g Canned tomatoes (purée)
• 40 g Butter
• 30 g Type 45 flour
• 400 ml Whole milk
• 1 pinch Nutmeg
• 250 g Dry lasagna sheets
• 200 g Grated cheese (mozzarella or blend)
• 150 g Mozzarella