Cannelloni with Cheese and Spinach

Name: Cannelloni with Cheese and Spinach
Prep time: 20 min
Cook time: 35 min
Total time: 55 min
Cuisine: Italian
Ingredients: 340 g spinach; 1 onions; 1 1/2 tbsp olive oil; 2 1/2 tbsp butter, unsalted; 4 tbsp white flour (all purpose); 2 cups milk, partly skimmed, 2%; 1 pinch salt; ground pepper to taste; 1 3/4 cup ricotta cheese; 3/4 cup Parmesan cheese; 2 eggs size large; 1 pinch nutmeg; 12 cannelloni