Cabbage rolls with mushroom filling

Ingredients

• 12 blanched savoy cabbage leaves
• 500 g mushrooms
• 1 onion
• 1 clove of garlic
• salt, pepper
• 1 ts dried thyme
• 250 g curd (approx. 20% fat)
• 2 egg yolks
• 2 tbs breadcrumbs
• 150 ml vegetable broth
• 150 ml cream
• 250 ml milk
• 1 tbs cornstarch
• 2 tbs coarse-grained mustard
• 1 tbs mustard
• sugar to taste