Preheat the oven to 375°F (190°C).

Cook the pasta according to package instructions until al dente. Drain and set aside.

In a large skillet, heat olive oil over medium heat. Add minced garlic and chopped red onions, cooking until fragrant and translucent.

Add the fresh spinach to the skillet and cook until wilted.

In a large mixing bowl, combine the cooked pasta, spinach mixture, ricotta cheese, shredded mozzarella cheese, grated Parmesan cheese, and a beaten egg. Season with salt and pepper.

Transfer the mixture to a greased baking dish and spread evenly.

Sprinkle with additional mozzarella and Parmesan cheese on top.

Bake in the preheated oven for 25-30 minutes, or until the top is golden and bubbly.

Let cool slightly before serving.