Bring a large pot of water to a boil and add a pinch of salt.
Add the broken spaghetti and cook until al dente according to package instructions, then drain well and set aside.
In a medium bowl, whisk together the eggs, grated Parmesan, 1/4 teaspoon salt, and 1/4 teaspoon pepper until combined.
Heat 1 tablespoon olive oil in an 8–10 inch nonstick skillet over medium heat.
Add the drained spaghetti and 1/4 cup marinara to the skillet and sauté briefly until heated through and coated with sauce.
Pour the egg and cheese mixture evenly over the spaghetti, tilting the pan so the eggs cover the pasta.
Reduce heat to low, cover, and cook until the bottom is set and the frittata slides slightly in the pan, about 4 minutes.
Use a plate to invert the skillet and flip the frittata, then slide it back into the pan and cook the second side until just set, about 3 minutes.
Slide the frittata onto a plate, slice, and serve warm.