Preheat your oven to 350°F. While the oven heats, cut the chicken into ½-inch cubes and set aside. Make sure your spinach is fully thawed and squeezed dry—this is crucial to prevent a soggy crust, so don't skip this step. Shred the cheese if not already done, and have both pie crusts out of the refrigerator so they can come to room temperature slightly, making them easier to work with.

In a medium bowl, whisk together the eggs, milk, garlic powder, nutmeg, salt, and black pepper until fully combined and smooth. This custard will bake into a creamy, flavorful base that holds the filling together. Set aside.

Place one pie crust into a 9-inch pie dish. In a large bowl, combine the cubed chicken, squeezed spinach, and shredded cheese—I like to use my hands to gently mix these together so the cheese distributes evenly throughout. Spread this mixture evenly over the bottom crust, leaving about ½ inch of space from the edge. This spacing gives room for the custard to be poured in without overflowing.

Carefully pour the custard mixture from Step 2 over the chicken and spinach filling, distributing it evenly across the entire surface. Place the second pie crust on top and gently press the edges together to seal. Trim any excess dough hanging over the edge, then cut 4-5 small slits in the top crust—these vents allow steam to escape during baking and prevent the crust from puffing up unevenly.

Place the pie on a baking sheet (this catches any drips and makes oven cleanup easier) and bake for 50 minutes, or until the top crust is golden brown and a knife inserted into the center comes out clean. The pie will continue to set slightly as it cools, so don't overbake—a slightly jiggly center is fine when it comes out of the oven. Let the pie rest for 10 minutes before slicing; this allows the filling to set up properly and makes serving much cleaner.