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.
Add ground beef and sausage and brown over medium-high heat, breaking up meat as it cooks.
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!).
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).
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.
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.
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).
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!)
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.
Assemble Lasagna:
Heat oven to 360°F (180°C). Prepare Lasagna noodles according to package directions (I used an oven-ready kind that asked to soak the noodles for a couple of minutes in just-boiled water).
Set aside 1 cup of the Béchamel sauce.
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 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.
Bake 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 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.
Notes
Ingredient notes
Lasagna sheets: I used oven ready lasagna sheets and I soaked them in just-boiled water for a few minutes before using. Fresh lasagna sheets can also be used.
Ricotta: This is not necessarily classically Italian, but it is classic in American-Italian lasagna recipes. My lasagna works without ricotta if you want to omit it.
I strongly recommend you don’t take any shortcuts when it comes to the Béchamel (besciamella) and the Bolognese sauce here. My recipe is not fancy or anything, but it does take time to make. In my humble opinion, the time is worth it.
For more tips, ingredient substitutions and notes on the sauce recipes (plus through step by step photos/explanations), I recommend to go check out the post on Béchamel Sauce and the post on Bolognese Sauce.
Recipe tips
Make sure to allow enough time to complete all of the components you need to assemble the lasagna. Especially the meat sauce will take a few hours to cook, and it’s best to allow it to cool before layering the lasagna.
Make sure you remember to set aside 1 cup of the Béchamel sauce before layering the casserole. You need this to cover the final layer of lasagna noodles. For some reason I was always short on sauce for the top, no matter how careful I tried to measure. Now I always set some aside first. It’s important to have enough sauce for the final layer, otherwise the top of the lasagna will be dry.
Do not skip the resting time after baking, otherwise your Lasagna will fall apart when serving.
Make ahead
You can assemble the lasagna up to 24 hours ahead of baking it.Allow both sauces to cool to room temperature before assembling your casserole. Tightly cover the dish with plastic wrap and store in the fridge.Once ready to bake, heat the oven to 375°F (190°C). Uncover the lasagna and allow it to sit on the counter while the oven pre-heats.Once the oven is hot, place the dish with the lasagna on a baking sheet on the middle rack and bake for 45-60 minutes, until piping hot and bubbly all the way through.How do I serve Lasagna without it collapsing?– Follow the layering process exactly to ensure your Lasagna layers will cling together. – Make sure to allow the Lasagna to rest for 15-20 minutes before serving. – Slice the Lasagna with a knife, not with a wooden spoon or spatula (use a blunt knife/butter knife! otherwise you’ll scratch your pan). – Slide a thin offset spatula below the Lasagna slice to fully release it from the pan before lifting it out with our largest offset wooden/silicone spoon or spatula you own. – Carefully place the slice on the wooden spoon on the plate at a slight angle (make sure the spoon rests on the plate). Use a knife or thin offset spatula to slowly slide the Lasagna off the spoon and onto the plate.These detailed steps are making me sound completely insane, but that’s the exact process I go through to serve neat slices. So… Feel free to laugh at me, but this works ?