Spaghetti Carbonara Pie

Name: Spaghetti Carbonara Pie
Prep time: 20 min
Cook time: 1 h 50 min
Total time: 1 h 50 min
Yield: 8 portions
Ingredients: unsalted butter; 4 oz Parmesan cheese; 3 oz Gruyère cheese; 1 tbsp dried parsley; ¼ tsp black peppercorns; 4 oz yellow onions; 2 garlic cloves; 8 oz pancetta; 8 oz cremini mushrooms; 60 oz water; 1 tsp salt; 4 ½ oz baby spinach; 16 oz spaghetti; 8 oz whole milk; 4 oz heavy whipping cream; 3 large eggs; 2 egg yolks; 1 oz extra virgin olive oil