Make the Spinach and Herbs: In a 10-inch skillet, heat the olive oil over medium heat. Add the onion and garlic and cook them in the oil for about one minute or until they are fragrant. Add the spinach and cook until it's wilted, stirring frequently. Add the salt and pepper, stir, and turn off the heat. Add the chopped herbs, stir to combine, and transfer the mixture to a bowl or plate to cool.
Make the White Sauce: In the same skillet, melt the butter over medium heat. Once it's melted, add the flour and stir to combine. Cook the flour and butter for 30 seconds to a minute, stirring continuously.
Grab a whisk and add the milk, a little at a time, whisking continuously. Adding the milk in batches will ensure your sauce is smooth. Once you've added all the milk, cook the sauce for another minute or so until it's thickened enough to coat the back of a spoon. Turn off the heat and transfer the sauce to a bowl.
Make the Ricotta Filling: In a small mixing bowl, combine the ricotta cheese, egg, salt, and pepper. At this point, you're ready to start assembling the lasagna, so place all of the fillings near your baking dish.
Assemble the Lasagna: Spoon enough white sauce to lightly coat the bottom of an 8x8" baking dish. Place two uncooked lasagna noodles on top of the sauce.
Top the noodles with 1/3 of the spinach-herb mixture and spread it into an even layer. Top the spinach with 1/3 of the ricotta mixture. Top the ricotta with 1/4 each of provolone and parmesan cheese. Place two more noodles on top of the cheese.
Spread about 1/2 of the white sauce on the noodles. Top with another layer of the spinach-herb mixture (leaving enough for one more layer), followed by more ricotta (leaving enough for one more layer). Add another layer of provolone and parm (leaving 1/2 for the rest of the layers). Top the cheese with two more noodles.
Top the noodles with the rest of the spinach mixture, followed by the rest of the ricotta. Add more cheese (leaving enough for the last layer). Top the cheese with the last two noodles.
Spread the rest of the sauce over the noodles. Top the sauce with the rest of the cheese. Sprinkle the Italian seasoning over the top.
Bake the Lasagna: Cover the baking dish with foil and bake the lasagna for 20 minutes. Uncover and bake for 5 to 10 minutes longer or until the cheese is melted on top. Rest the lasagna for a few minutes before slicing and serving.
Notes
For this recipe, the prep time includes the time it takes to prep the ingredients (chopping, shredding, etc) and the cooking steps done before assembling the lasagna. The cook time is the estimated time for the lasagna to bake.I like to use Barilla oven-ready flat lasagna noodles because they easily fit into an 8x8" pan. You can use other kinds of no-bake lasagna (the ones with wavy edges), but you will need to break them to fit into the pan.Make-ahead tips: You can assemble the whole lasagna a day in advance and then bake it later. Cover it with foil and store it in the refrigerator for up to a day ahead. Let it sit out at room temperature while you preheat the oven. You may need to add a few extra minutes to the baking time (5 to 10 minutes or so).