The creamiest vegan lasagna with spinach and mushrooms

Ingredients

• 1 1/3 lbs button mushrooms
• 1 onion
• 2 cloves garlic
• 1 tbsp thyme
• 1 tbsp olive oil
• 7 oz spinach
• 1/2 cup margarine
• 3 tbsp flour
• 480 ml soy milk
• 2 tbsp nutritional yeast
• 1 tsp nutmeg
• 1 lb tomato purée (passata)
• 1 lb lasagna noodles
• salt
• pepper
• thyme (for garnish)
• 1 tsp Kitchen Stories Veggie Wunder seasoning (optional)