Mushroom and Spinach Strata

Name: Mushroom and Spinach Strata
Prep time: 15 min
Cook time: 2 h 10 min
Total time: 2 h 10 min
Yield: 12 portions
Ingredients: ½ oz extra virgin olive oil; 12 oz dried bread cubes; 8 oz Gruyère cheese; 3 oz Parmesan cheese; 4 oz red onions; ½ tsp dried parsley; ½ tsp dried thyme; 16 oz cremini mushrooms; 4 oz baby spinach; 2 oz sun-dried tomatoes, in oil; 20 oz whole milk; 10 large eggs; 1 tbsp Dijon mustard; 1 tsp salt; ¼ tsp ground black pepper