In a medium saucepan, melt butter. Add garlic and sauté until fragrant. Whisk in flour and cook for 2-3 minutes. Gradually pour in half-and-half and milk, cooking until thickened. Stir in cheese, salt, pepper, and nutmeg until smooth.

In a large skillet, heat olive oil. Add mushrooms and cook until browned. Stir in spinach and cook until just wilted. Remove from heat and let cool.

In a mixing bowl, combine ricotta, eggs, and seasonings. Mix until creamy, then fold in the cooled vegetable mixture.

Preheat your oven to 375°F. Spread a thin layer of béchamel in a greased baking dish. Layer noodles, half the cheese mixture, mozzarella, and repeat. Finish with béchamel and remaining mozzarella.

Cover with foil and bake for 50 minutes. Remove foil and bake for an additional 10 minutes until golden brown.

Let it cool for 15 minutes before slicing and serving.