6 sheets phyllo pastry (17x13-inches each), defrosted if frozen
4 tablespoons unsalted butter, melted
FILLING:
1 tablespoon olive oil
1 large onion, finely chopped
20 ounces frozen chopped spinach, thawed and squeezed dry
2 cups ricotta cheese
8 ounces crumbled feta cheese
8 ounces grated Monterey Jack cheese
2 large eggs
3 tablespoons finely chopped fresh dill
3 tablespoons finely chopped fresh parsley
1/4 teaspoon salt
1/4 teaspoon freshly ground black pepper
Preheat oven to 350°F. Butter a 13x9x2-inch baking dish or spray with nonstick spray. In a medium skillet, heat the olive oil over medium heat for about 1 minute. Add the onions and cook until softened, about 5 minutes, stirring often. Set aside. In a large bowl, stir together onion, drained spinach, ricotta, feta, jack cheese, eggs, dill, parsley, salt and black pepper. Spread half of filling in baking dish. Cover with 2 pieces of the phyllo pastry (just tuck the edges in on the sides). Brush pastry lightly with melted butter. Top with one piece of phyllo. Tuck in any overhanging edges. Spread remaining filling over phyllo. Top with 2 more pieces of phyllo and brush lightly with butter. Top with remaining phyllo sheet and brush with butter. Use a sharp knife to mark 12 squares by cutting through the top layers of pastry. Bake until phyllo topping is golden and filling is bubbling gently, about 45 minutes. Use a sharp knife to cut through the marked squares. Serve warm.