Cook lasagna noodles according to package directions. Drain and lay noodles on a baking sheet in order to keep them from sticking together.
While the pasta is cooking, heat the olive oil over medium. Add onions and cook until softened, 3 minutes. Add garlic and cook an additional minute. Add the greens and cook until wilted, 5-10 minutes, depending on variety of green used. Remove from heat and let cool slightly.
In a medium bowl, mix together the ricotta, half the mozzarella, egg, salt, and pepper. Stir in the greens mixture.
Spread 1/2 cup marinara sauce in the bottom of an 11x7-inch casserole pan.
Assemble the rolls by spreading about 1/4 cup of the cheese mixture, leaving an inch at the end. Roll up pasta, ending with the uncovered edge.
Place each roll in the casserole pan with the seam on the bottom. Continue until all noodles are rolled.
Pour remaining pasta sauce over rolls, then sprinkle with remaining mozzarella. Cover with foil.
Bake for 25-35 minutes, until cheese is melted and bubbly. Let cool 5-10 minutes before serving.