Bring a large pot of salted water to a boil, add the broken spaghetti, and cook until al dente according to the package directions. Drain thoroughly and set aside.
In a medium bowl, whisk together the eggs, grated Parmesan, salt, and black pepper until combined.
Heat the olive oil in a 9–10 inch nonstick skillet over medium heat. Add the cooked spaghetti and marinara sauce, tossing to combine and warm through for 1–2 minutes.
Pour the egg mixture evenly over the spaghetti in the skillet, gently stirring once to distribute, then tilt the pan so the eggs cover the spaghetti evenly.
Reduce heat to low, cover the skillet, and cook until the bottom is set and the edges lift easily, about 4 minutes.
Carefully invert the frittata onto a plate, then slide it back into the skillet to cook the other side until just set, about 3 minutes.
Slide the frittata onto a cutting board or plate, cut into wedges, and serve warm.