Mushroom Bolognese Lasagna

Name: Mushroom Bolognese Lasagna
Prep time: 30 min
Cook time: 1 h 45 min
Total time: 1 h 45 min
Yield: 8 portion
Ingredients: 200 g cheese; 200 g button mushroom; 130 g carrot; 130 g yellow onions; 1 garlic clove; 1 piece Chinese celery; 400 g tomato sauce; 50 g olive oil; 500 g minced beef; 1 chicken stock cube; 1 tsp oregano, dried; 1 bay leaf, dried; 1 - 2 pinch pepper, powder; 800 g milk; 60 g unsalted butter; 70 g plain flour; ½ tsp salt; ¼ tsp nutmeg, ground; unsalted butter; 18 pre-cooked lasagna pasta