There have been so many nights when I craved lasagna but didn't want to get stuck with the usual leftovers. If you've felt the same way, this small-batch version solves all your problems! It's easy enough to throw together on a weeknight and is the perfect size for two (or three) servings.
Heat the olive oil in a medium saucepan over medium-high heat. Add the onion, garlic and 1/2 teaspoon salt and saute until the onion is translucent and softened, stirring occasionally, about 4 minutes. Add the ground beef and use a wooden spoon to break it into pieces. Cook, stirring occasionally, until no longer pink, 4 to 6 minutes. Add the oregano and cook 1 minute. Stir in the marinara and let simmer while you make the ricotta mixture.
Lightly beat the egg in a medium bowl. Stir in the ricotta, parsley, basil, 1/2 cup mozzarella and 1/2 cup Parmesan until combined.
Begin to layer the lasagna, spread 2 tablespoons marinara sauce evenly over the bottom of an 8 1/2-by-4 1/2-inch loaf pan. Cover with 1 lasagna noodle. Spread on 1/3 cup of the ricotta mixture followed by 1/2 cup marinara sauce. Top with another noodle. Repeat layering 4 more times, ending with the sauce. Top the final layer with the remaining 1/2 cup mozzarella and 2 tablespoons Parmesan. Bake until the noodles are tender and the cheese is melted and bubbly, about 30 minutes. Let stand 10 minutes before serving.