Preheat oven to 350°F
Defrost the spinach by setting out on the counter for several hours until thawed. Once it is no longer frozen, place in a fine mesh strainer and press to excrete all excess water In a medium skillet, heat the olive oil over medium heat for about 1 minute. Add the chopped onions and cook until softened, about 5 minutes, stirring often. Set aside
In a large bowl, stir together onion, drained spinach, ricotta, feta, Monterey jack cheese, eggs, dill, parsley, salt and black pepper
Spread cheese filling in baking dish. Cover with 2 pieces of the phyllo pastry (just tuck the edges in on the sides). Repeat the layering process over and over again until both the cheese filling and phyllo sheets are gone. (similar to layering lasagna)
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
Notes: *If covered tightly and refrigerated, this pie can be assembled early in the day and baked later. Cold pot pie will probably need to bake an additional 5 minutes.