Ricotta and Spinach Stuffed Fazzoletti (fazzoletti alla farcia di magro)

Ingredients

• 1 onion, chopped
• 2 garlic cloves, chopped
• 1/4 cup (60 ml) olive oil
• 1 can (28 oz/796 ml) plum tomatoes, crushed with your hands (or crushed tomatoes)
• 8 cups (200 g) baby spinach, coarsely chopped
• 2 tbsp (30 ml) olive oil
• 1 garlic clove, finely chopped
• 2 1/4 cups (560 ml) ricotta cheese (1 1/2 containers of 425 g each)
• 1 cup (70 g) Parmesan cheese, freshly grated 
• 1 1/2 cups (150 g) mozzarella cheese, grated
• Ground nutmeg, to taste
• Fresh lasagna noodles, cut into two squares each (1 package of 360 g)
• Basil leaves, for garnish