Creamy mushroom sauce

Name: Creamy mushroom sauce
Prep time: 5 min
Cook time: 15 min
Total time: 20 min
Cuisine: American
Ingredients: 1 tablespoon butter; 2 tablespoons oil; 5 cups portabellini/chestnut mushrooms, halved/sliced (approximately 500g/ 1 pound); 2 sprigs fresh thyme; 2 garlic cloves (crushed); 1 cup cream; 1 cup milk mixed with 3 teaspoons corn flour/corn starch; 1-2 tablespoon lemon juice (to taste); salt & pepper to taste; 2 tablespoons chopped parsley