In a skillet, heat the 2 teaspoons of olive oil over medium heat. Add the sliced mushrooms, diced onion, diced bell pepper, and minced garlic. Sauté for about 5-7 minutes until the vegetables are softened and fragrant.
In a mixing bowl, combine the ricotta cheese, egg, kosher salt, and ground black pepper. Mix until well combined and set aside.
In your crockpot, layer half of the pasta sauce on the bottom. Then, add half of the uncooked whole wheat pasta, followed by the sautéed vegetable mixture. Spread the ricotta mixture on top, followed by half of the shredded mozzarella cheese and half of the fresh spinach.
Repeat the layering process with the remaining ingredients: add the rest of the pasta sauce, the remaining pasta, the rest of the sautéed vegetables, the remaining ricotta mixture, the last of the mozzarella cheese, and finish with the remaining fresh spinach.
Cover the crockpot and cook on low for 4-5 hours or on high for 2-3 hours, until the pasta is tender and the cheese is melted.
Once cooked, stir the pasta gently to combine all the layers. Serve warm, topped with fresh basil or parsley for garnish and a sprinkle of Parmesan cheese if desired.
