Simmer down the sauce for 10 minutes or so, so that the seasoning infuses the meat sauce.
Take from the heat when the meat sauce is ready, and take out the bay leaf, so to discard it. Keep meat sauce aside.
Béchamel Sauce
Keep a sauce pan over a lower heat setting and melt the butter.
½ Stick Butter
Stir in all-purpose flour with a whisk and keep on stirring to create the roux.
5 Tablespoon All-Purpose Flour
The flour and butter will mix up, and it will start to bubble and that is when you gradually pour in the milk with a whisk so that no lumps are formed. Increase heat to a medium flame if needed.
2½ Cups Milk
Add ground nutmeg, black pepper and salt to season.
pinch Nutmeg, ¼ Teaspoon Black Pepper, ½ Teaspoon Salt
Whisk in the shredded cheese and shredded Parmesan cheese and cook down the sauce to desired consistency. The sauce is ready when it appears thicker and when it sticks to your whisk.
½ Cup Shredded Cheese, ½ Cup Shredded Parmesan Cheese
To Assemble Lasagna
Preheat oven to 320 Fahrenheit (160 degree Celsius).
The lasagna contains 5 pasta layers. The bottom needs to be layered first, always with béchamel sauce, so that the pasta sheets soak up and get soft. Each layer starts with pasta sheets, then you follow with a thin layer of béchamel sauce and at last the tomato sauce over that.
15 Lasagna Sheets
The full assembly order for the lasagna layers: 1. Béchamel sauce, 2. Pasta sheets, 3. Béchamel sauce, 4. Meat Sauce, 5. Pasta sheets, 6. Béchamel sauce, 7. Meat sauce, 8. Pasta sheets, 9. Béchamel sauce, 10. Meat sauce, 11. Pasta sheets, 12. Béchamel sauce, 13. Meat sauce, 14. Pasta sheets, 15. Béchamel sauce, 16. Meat sauce, 17. Cheese topping.
The shredded cheese and Parmesan are spread across and form the topping at the end.
½ Cup Shredded Cheese, ¼ Cup Shredded Parmesan Cheese
Cover the baking dish with aluminum and bake first for 30 minutes covered at 320 Fahrenheit (160 degree Celsius).
Take out the baking dish from the oven and uncover the dish. Take it back to the oven and continue to bake for another 25-30 minutes or so at the same temperature uncovered. The lasagna is ready when it's slightly crispy and golden at the top.
Notes
15 Ounces = 1 can Tomato Sauce. For Europe and the rest of the world, use 440 ml cans.1 Stick Butter = 4 Tablespoons9 Ounces oven-ready Lasagna from Barilla contains 15 Sheets. That's 250 grams, by the way.You need to either use oven-ready lasagna sheets that don't need to be pre-boiled, or you need to pre-boil your sheets (which is extra work), or you use fresh lasagna sheets made from scratch or bought in store (but the dimensions will be different).Tip: You can switch the ground beef with ½ ground beef and ½ ground pork. This meat combo is common in Europe.The Allspice is optional because not everybody has them at home, but it is a cool seasoning, that adds so much flavor to this dish. Try it with finely crushed allspice!