Cook the macaroni according to package instructions until al dente, about 8-10 minutes. Drain and set aside.

In a skillet, heat olive oil over low heat. Sauté chopped onion and garlic for 3-4 minutes until soft.

Stir in spinach and cook for 1 minute until wilted. Remove from heat.

Puree the spinach mixture in a blender until smooth.

In a saucepan, melt butter over low heat. Whisk in flour to create a roux.

Gradually whisk in milk, stirring until thickened, about 2-3 minutes. Add spinach puree and cheddar cheese, stirring until melted.

Combine the cheese sauce with the macaroni, ensuring all pieces are coated. Season to taste.

Serve warm with additional cheese or parmesan if desired.