- Preheat oven to 375°F.
- Heat a large skillet over medium heat. Once the skillet is hot, add 1 tsp olive oil.
- Add the shallot to the skillet; cook, stirring frequently, until softened, 1-2 minutes.
- Roughly chop the spinach, add to the skillet with the shallot. Cook, stirring frequently, until spinach has wilted, 2-3 minutes.
- In a small bowl, mix together the tomato sauce, Italian seasoning, and salt.
- Grate the Parmesan and mozzarella.
- In a large bowl, combine the ricotta, egg, Parmesan, and half of the mozzarella. Add the spinach mixture to the bowl and stir to combine.
- Coat the bottom of a small baking dish or loaf pan with tomato sauce. Add one lasagna noodle on top of the sauce. Add ¼ cup of sauce, one-third of the spinach mixture, and a noodle. Repeat this step twice more until you have formed three layers. Top with a final noodle, the rest of the sauce, and the other half of the mozzarella cheese.
- Cover with foil and bake for 20 minutes. Remove the foil and bake for another 5 minutes.