Speedy Spanikopita

Preheat the oven to 350 degrees F (175 degrees C). Grease a large baking sheet lightly with cooking spray.

Heat a large pan over medium-high heat and coat with cooking spray. Saute spinach, green onions, dill, garlic, salt, and pepper until spinach wilts and begins to release its liquid, 3 to 5 minutes.

Combine mozzarella, Parmesan, and feta cheeses in a large bowl. Add egg and the spinach mixture and mix thoroughly.

Lay 1 puff pastry sheet on the baking sheet. Trace a wet fingertip around the edge to moisten. Spread the spinach and cheese mixture in the center, leaving a 1/2-inch border. Lay the second sheet of pastry on top and push down the edges to seal. Make two knife slits on top to allow steam to escape. Spray the top with cooking spray.

Bake in the preheated oven until golden brown, 15 to 20 minutes. Let cool for 5 minutes and slice into sections using a pizza cutter.