Heat a drizzle of olive oil in your skillet over medium heat. Add the chopped onion and cook until softened and translucent, about 3-4 minutes. Stir in the minced garlic and cook until fragrant, roughly 30 seconds. Add the ground beef, breaking it apart with your spoon. Cook until browned and no longer pink, about 6-8 minutes. Season with salt and pepper.
Once the beef is browned, stir in the chopped fresh spinach. Cook until wilted, about 2 minutes. Pour in the crushed tomatoes along with the dried Italian herbs. Stir everything until well combined. Bring the mixture to a gentle simmer.
Add the broken lasagna noodles directly into the skillet, making sure they’re submerged in the sauce. If necessary, add about 1 to 1 1/2 cups of water to cover the noodles. Stir to combine, then cover the skillet with a lid. Simmer gently for 12-15 minutes, stirring occasionally, until the noodles are tender and have absorbed the flavors.
Once the noodles are cooked through, dollop spoonfuls of ricotta cheese evenly over the top. Sprinkle with mozzarella and Parmesan cheeses. Cover the skillet again and let it cook for another 3-5 minutes, or until the cheese melts into a gooey, golden blanket over the lasagna.
Turn off the heat and let the skillet rest for a few minutes. This helps the layers set slightly and makes serving easier. Scoop portions onto plates and garnish with extra Parmesan or fresh basil if desired. This skillet pairs wonderfully with a crisp salad or some garlic bread.