• Prep:

  As a timeline, you'll first get your Bolognese sauce going. This sauce needs to simmer for 1-2 hours to fully develop its flavor, so it's the first thing you'll want to make.

  Once your Bolognese sauce is done, you'll want to make your creamy white sauce - aka the Béchamel or Besciamella. The Bolognese will cool down as you make the white sauce, plus you will need to allow the Béchamel 15-20 minutes to cool down as well before you can assemble and bake your Lasagna.

  Get your ingredients ready.
  

Make Bolognese sauce (meat sauce):

• Heat olive oil in a large, wide pan over medium heat. Add onion, carrot, celery and garlic and sauté slowly until onion has fully softened, about 8-10 minutes.
  2 tablespoons olive oil, 1 medium onion, 2 medium carrots, 2 sticks celery, 3 cloves garlic
  
• Add ground beef and sausage and brown over medium-high heat, breaking up meat as it cooks.
  1 pound ground beef, 1 pound ground Italian sausage
  
• Reduce the heat to medium. Stir in tomato paste, Italian seasoning, salt and pepper. Cook for 1-2 minutes, until tomato paste has roasted and smells flavorful (do not burn!).
  ¼ cup tomato paste, 2 teaspoons Italian seasoning
  
• Pour in red wine, scraping any browned bits off the bottom of the pan. Simmer until wine has reduced by ⅓ (do not simmer any longer, or wine may become too acidic).
  1 cup red wine
  
• Stir in crushed tomatoes and balsamic vinegar, add bay leaves. Bring to a boil once, then reduce heat to a simmer and cover with a lid.

  Simmer sauce covered for 1-2 hours, then remove lid and simmer for 15 more minutes, until rich and thick. Season with sugar, salt and pepper to taste. Allow to cool to room temperature.
  1 (28-oz) can crushed tomatoes, 2 teaspoons balsamic vinegar, 2 bay leaves, 1 teaspoon sugar, salt and pepper
  

Make Béchamel (white sauce):

• Melt butter in saucepan over medium heat (saucepan needs to hold at least 2 quart).

  Whisk flour into butter and cook, whisking constantly, for 2-4 minutes. Flour must not brown.
  8 tablespoons butter, ¾ cup flour
  
• Gradually whisk milk into flour/butter mixture, do not allow lumps to form. Once all milk has been added, reduce heat to medium-low and simmer until sauce has thickened, whisking constantly (if sauce hasn't thickened after 5 minutes, heat setting is too low – increase a little until sauce is just bubbling and thickens).

  Note: If you added too much flour, the sauce will be paste-like and you'll need to thin it out a little until it is creamy but thick. Do not add too much milk, or your Lasagna won't hold together. Make sure to measure your flour correctly initially!)
  5 cups milk
  
• Stir parmesan cheese and ricotta (if using) into the sauce, then season with ground nutmeg and add salt and pepper to taste. Allow to cool for 15-20 minutes.
  ⅛ teaspoon ground nutmeg or more to taste, 1 cup grated Parmesan, 1 cup ricotta cheese, salt and pepper to taste
  

Assemble Lasagna:

• Heat oven to 360°F (180°C). Prepare Lasagna noodles according to package directions (some need to be soaked or boiled, others can be used dry.)

  Set aside 1 cup of the Béchamel sauce.
  1 (16-oz) box oven-ready lasagna sheets
• Spread a thin layer (a few tablespoons) of Béchamel sauce in a 9x13 inch (22cm x 33cm) casserole dish. Top with one layer of Lasagna noodles. Top with ⅓ of meat sauce. Top with ⅓ of remaining Béchamel sauce (sprinkle with shredded mozzarella cheese, if desired).

  Repeat layers two more times (lasagna noodles - meat sauce - béchamel sauce; lasagna noodles - meat sauce - béchamel sauce).
  
• Add a final layer of lasagna noodles, then gently press down on the lasagna until the sauce comes up around the noodles (this helps the lasagna to stick together and just makes it that much better for some reason.)
  
• Top with the 1 cup of Béchamel sauce you set aside. Top with 1 cup grated Parmesan cheese and with 1 cup shredded Mozzarella cheese.
  1 cup grated Parmesan cheese, 1 cup shredded mozzarella cheese
  
• Bake your Lasagna for 30-45 minutes, until bubbly and lightly browned on top (check Lasagna noodle package for baking time required for your exact noodles).

  Allow the Lasagna to rest on a cooling rack on the counter for 15-20 minutes before slicing to serve. Sprinkle with chopped fresh parsley, if you like.
  2 tablespoons finely chopped fresh parsley