Preheat your oven to 375 degrees. This initial step is essential, as you want your casserole to bake evenly and thoroughly. Preheating ensures that the cheese will melt beautifully and that the flavors meld together perfectly.
Chop or tear the spinach leaves into small pieces. This helps them cook down quickly and distribute throughout the casserole. Add olive oil to a large skillet, heating it over medium-low. Once the oil is warm, toss in the spinach and sauté until just wilted, which should take about 3 to 4 minutes. You want it to retain some texture so it doesn’t turn mushy.
In a large mixing bowl, combine the cooked penne, marinara, wilted spinach, and artichokes. Toss everything together gently to ensure that the marinara evenly coats the pasta and vegetables. The rich sauce will be the backbone of your dish, providing moisture and flavor.
In another large mixing bowl, combine the cheeses (cottage cheese, shredded mozzarella, and ricotta), egg white, oregano, black pepper, red pepper flakes, and salt. Mix until smooth and creamy. This mixture will add richness and a delightful creaminess that contrasts beautifully with the pasta.
Grab a 9" x 13" casserole dish. Start layering by adding half of the penne mixture, followed by half of the cheese mixture. Repeat, ending with the cheese mixture on top. This layering technique not only makes the casserole visually appealing but also allows for the flavors to meld as it bakes.
Sprinkle parmesan over the top of the casserole, along with a bit more freshly ground black pepper, if desired. The parmesan will create a beautiful golden crust as it bakes, adding an extra layer of flavor and texture.
Bake in the preheated oven for about 30 minutes or until hot and bubbly. You’ll know it’s ready when the top is golden and the cheese is melted. Keep an eye on it towards the end to avoid over-browning.
Once baked, remove it from the oven and let it cool slightly before serving. This brief resting period helps the casserole set up a bit, making it easier to serve and enjoy.
Serve warm, and watch as friends and family dig in with delight. The Artichoke Spinach Penne Casserole is sure to be a crowd-pleaser!