Bring a large pot of salted water to boil and cook spaghetti until just tender, about 8 minutes, or as package label directs. Drain, transfer to a large bowl and toss with olive oil to coat. Let cool to room temperature.
Cook turkey bacon in a large skillet over medium-high heat until crisp, 5 to 8 minutes. Remove bacon to paper towels to drain. Discard all but 1 Tbsp. of fat in skillet.
Preheat broiler to high. Whisk together eggs, Parmesan, garlic, 1/2 tsp. salt and 1/4 tsp. pepper in a bowl. Pour over spaghetti and toss to coat. Crumble bacon into bowl and mix well.
Place skillet on stove over medium-low heat and add egg-and-spaghetti mixture, spreading into an even layer with a spatula. Cook until bottom is well-browned, about 8 minutes, sliding a spatula underneath frittata occasionally to loosen.
Place pan under broiler and cook until top is golden and set, about 3 minutes. Cut frittata into wedges and serve.