In a large skillet over medium heat, sauté the onion in the olive oil until golden. Add the tomatoes, salt, pepper and basil. Reduce heat and simmer for about 20-30 minutes, until the sauce has reduced.
In a large bowl, whisk together the flour, milk, water and 1 egg together until smooth.
Place a large skillet or griddle over low heat. Use butter to grease the surface. Pour 1/8 cup batter onto the hot surface. Let the batter to cook through, but not turn golden. Use a spatula to remove and set aside. Re-grease the surface and repeat until all the batter is used. Ideally, the mixture will yield 12 sheets of pasta, 3×5 or 4×6 inches wide. (Note: if using a skillet, they can be round in shape.)
In a large bowl, add the ricotta, Parmigiano cheese, remaining egg, parsley and salt. Mix together until creamy.
Carefully fill the center of each pasta sheet with 2 heaping tablespoons of the ricotta mixture. Fold one side over the other to make to enclose. Line them up in an oiled baking dish. Cover loosely with foil and bake at 350º F. for 30 minutes, until the sides are bubbling.
Serve immediately with a spoonful of tomato sauce and grated Parmigiano.
