Preheat the Oven: Preheat your oven to 375°F (190°C).
Sauté the Chicken: In a large skillet, heat some olive oil over medium-high heat. Add the chopped chicken pieces and cook until they are no longer pink in the center, about 5-7 minutes. Remove the cooked chicken from the skillet and set it aside.
Sauté the Aromatics: In the same skillet, add a bit more olive oil if needed. Sauté the chopped onion until it becomes translucent, about 3-4 minutes. Add the minced garlic and cook for another 1-2 minutes until fragrant.
Add the Spinach: Add the chopped spinach to the skillet and cook until it wilts down, about 2-3 minutes. Season with salt and pepper to taste.
Combine the Filling: In a large mixing bowl, combine the cooked chicken, white beans, sautéed spinach, crumbled feta cheese, ricotta cheese, grated Parmesan cheese, chopped dill, parsley, and mint (if using). Mix everything together until well combined.
Prepare the Phyllo Dough: Place one sheet of phyllo dough in the bottom of a greased 9x13-inch casserole dish, allowing the excess to hang over the edges. Brush it lightly with melted butter or olive oil. Repeat with 4-5 more sheets, layering and brushing each sheet as you go.
Add the Filling: Pour the chicken and white bean mixture over the layered phyllo dough.
Top with More Phyllo Sheets: Layer the remaining sheets of phyllo dough over the filling, brushing each sheet with butter or olive oil. Scrunch the excess dough hanging over the edges and tuck it in around the edges of the casserole dish to create a rustic look.
Bake: Place the casserole in the preheated oven and bake for about 30-35 minutes or until the phyllo dough is golden brown and the filling is bubbly.
Serve: Allow the casserole to cool for a few minutes before serving. Cut it into squares and enjoy your Spanakopita-inspired Chicken and White Bean Casserole loaded with protein!This casserole is a flavorful twist on traditional Spanakopita, with the added bonus of chicken and white beans for protein. It's a satisfying and nutritious meal that's perfect for dinner or a potluck gathering.