For the pasta pomodoro: Combine the tomato passata, olive oil, sugar, basil, garlic and 1 teaspoon salt in a wide, low-rimmed pot. Bring to a boil over medium heat, then reduce the heat and simmer, uncovered, for 20 minutes.
Meanwhile, bring a large pot of salted water to a boil. Cook the spaghetti until al dente, according to the package instructions, then drain. Toss the spaghetti with the pomodoro sauce.Let cool.
For the frittata: In a large bowl, mix the pasta pomodoro, Parmigiano-Reggiano, eggs, 1 teaspoon salt and 1/2 teaspoon pepper until well combined.
Heat the margarine in an 8-inch shallow skillet over medium-low heat. Add half of the pasta mixture and spread it over the skillet, keeping it thickest in the middle and thinner toward the edges. Cook, undisturbed, for 3 to 5 minutes. Flip the frittata over and cook the reverse side for another 3 to 5 minutes. (The pasta should be warmed through, and the outside should be crispy and nicely golden.) Transfer the frittata to a plate and repeat the same process with the second half of the pasta. Serve warm or at room temperature.
I prefer to use margarine instead of butter in this recipe, as it is less likely to burn.