Cook orzo according to package directions. Set aside.

Heat olive oil in a medium-sized pot over medium heat. Add onions, garlic, salt and pepper and saute for 1 minute or until onions are translucent. Add flour to form a roux and cook for an additional minute.

Add about 1/4 cup of the milk to the pot and whisk to work out any lumps from the roux. When lumps are worked out, add the remaining milk and whisk to combine. Bring to a simmer and cook until sauce has thickened, about 8 minutes.

Add chopped spinach to sauce and cook an additional 2 minutes or until spinach has cooked down. Remove sauce from heat.

Stir parmesan cheese into sauce. When cheese has melted, add cooked orzo to sauce and toss to coat. Garnish with extra parmesan cheese and serve immediately.