Heat oven to 350° F. In an ovenproof nonstick skillet, cook the bacon and garlic over medium heat until the bacon is crisp and the garlic is browned, 7 to 8 minutes.
Transfer the bacon to a paper towel-lined plate, then crumble. In a small bowl, smash the garlic until creamy.
Pour off all but 2 tablespoons of drippings from the skillet and return to medium-high heat. Add the garlic and eggs and cook, stirring, for 30 seconds.
Reduce heat to medium-low and continue cooking, without stirring, until the eggs are beginning to set at the edges, 3 to 4 minutes.
Add the crumbled bacon, tomatoes, Parmesan, ½ teaspoon salt, and ¼ teaspoon pepper. Transfer to the oven. Bake until the center is set, 10 to 12 minutes.
Toss the greens with the oil, vinegar, and ¼ teaspoon each salt and pepper. Serve with the frittata.