Moussaka is a classic, delicious casserole that can be made ahead and baked the day of serving or the parts can be prepared ahead of time and then assembled and baked the day you want to serve. It can be time consuming if doing everything on the day you want to serve it. This is where Greek cooking gets its bad wrap for time consuming meals. It isn’t so bad if you break it up though and have a plan. I am happiest when I have a plan. Things go smoother for me that way. I will almost always do it in different sessions not because of the length of prep time, that doesn’t bother me, the clean up takes too much time for me. Cooking for long periods of time doesn’t bother me, but cleaning does.
This has five layers. Layered potatoes, meat sauce, cheese, eggplant and bechamel. Traditionally, the potatoes and eggplant are fried, but eggplant holds the oil so well, I stopped frying and started baking the eggplant instead, years ago. You can also use sliced Italian zucchini instead of eggplant if you prefer. The meat sauce I use is the basic meat sauce I use with spaghetti during the week for a quick meal. It comes together really quickly and if you make a double batch, you can use it for more than one meal in the week.
First make the meat sauce. Saute the onions in the olive oil until tender. I will salt and pepper each step. Not a lot, just a little for each step. Add the ground beef and break up until it is evenly crumbled. It is good to have it as uniform in size as possible. Again, season with salt and pepper. Add the tomato paste and water and stir to combine. Let it simmer while you prepare the vegetables. When the sauce has simmered for about 45 minutes, add the cinnamon and cloves and turn off the heat. I’ve had people tell me they add garlic or oregano to this sauce, but I don’t. This is how I learned to make it and have never had any reason to change it.
Peel and slice the potatoes less than a 1/4 thick. (About as thick as you would slice if you were to continue to make french fries) Rinse and pat dry. Fry in oil until golden, flipping over if using a skillet to make sure both sides are golden. Do in batches so you don’t crowd the slices in the pan. Once golden, remove and drain on paper towels. Once all the potatoes are done, sprinkle with salt while still hot. Line the bottom of your casserole pan with the potatoes.
Wash and slice the eggplant or zucchini the same way. Brush the sheet pan with oil and line the pan with the zucchini, rubbing them in the oil and then flip them so they get oil on both sides. Sprinkle with salt and pepper and bake in a preheated 375º oven until golden brown.
Bechamel:
So, this takes some practice but it is nothing to be afraid of. First, heat the milk until hot and turn it off. It is best if it is hot, it can be warm, it just should not be cold. Next, melt the butter in another pot at a medium low heat. Whisk in the flour and whisk continuously until the mix starts to dry and pulls away from the pot. 
Slowly add the milk, a little at a time (about a cup at a time) whisking all the time to continuously incorporate the milk into the mix. Using hot milk protects the mix from developing lumps. Lumps are bad. You want it to be as creamy as possible. Add salt and pepper (some people don’t use pepper because it is a white sauce, but I like it, and holy smokes do not use white pepper, why, it seems not to be pepper at all) and continue on medium to medium high heat, stirring all the while until it comes to a boil and is thick, about 10 minutes. My analogy would be it should look like pudding (before it cools). Remove it from the heat. Beat egg yolks in a medium bowl. Temper the eggs by taking a cup of the bechamel from the pot and whisking into the eggs. Be quick about it. Don’t add the hot bechamel and let it sit, you will end up with cooked eggs. Once the eggs and bechamel are combined, pour into the bechamel and stir to combine. Add a sprinkle of nutmeg. If you are not ready to use it right away, put either parchment or wax paper (I don’t like using plastic wrap on hot food for health reasons) directly on top of it or it will develop a skin on it (like pudding).
To assemble:
You have already put the potato layer in the pan, now it is time to add the meat sauce. Layer it evenly in one layer. Use a slotted spoon so you get some sauce, but not too much sauce.
Top the meat layer with cheese. Then add the vegetable layer and top with the bechemel, smoothing the top. So now if I have Panko bread crumbs, I will mix 1/2 cup of Panko with 2 Tbl. of parmesan and 1 Tbl of olive oil together and sprinkle on top before putting in the oven. If I don’t have panko, I will sprinkle just the parmesan on top.
Bake at 375º for about 45 minutes until it is golden brown and the bechamel has set.
Let set for at least 15-20 minutes before cutting.
*For the meat sauce (called Kima):
*This makes a lot and you will have enough to use later with spaghetti
Extra Virgin Olive oil to coat the bottom of the pot
Vegetable oil or Canola oil for frying the potatoes
1 brown onion, cut in half and sliced
3 lbs ground beef
2 cans tomato paste and 3 cans of water
1 Tbl salt
1 Tbl pepper
1/2 tsp cinnamon
3/4 tsp cloves
1 cup shredded Kasseri or as a substitute you can use Asiago and Parmesan mix.
2 medium egglplant or 4-6 or so Italian Zucchini
*6 large potatoes (enough to cover the bottom of the casserole dish)
*I will usually peel and slice right into the pan and over lap quite a bit to measure before cooking to make sure I have enough because they shrink a little in size when cooked.
Bechamel:
This also makes more than you need. I spent too long worried I wouldn’t have enough until I just increased the recipe.
7 cups milk (any amount of fat except 0%)
2 sticks butter
3 egg yolks whisked
1 1/4 to 1 1/2 cups flour
salt and pepper to taste
sprinkle of nutmeg (not so much that it is even noticeable to taste, only so people think, hmmm)
Panko topping if using is 1/2 cup panko (unseasoned, Please do not use Italian bread crumbs) 2 Tbl parmesan cheese, 1 Tbl olive oil
Instructions
Heat oven to 375º (convection if you have it)
Coat the bottom of the pot with Olive Oil and heat over medium heat. Add the onions a sprinkle with a little salt and pepper and cook until tender. Add the ground beef and saute until brown, breaking up the meat until uniform in size. Add the tomato paste and water, salt and pepper and after it comes to almost a boil, reduce to simmer and cook for about 45 minutes. Once you are ready to turn it off, add the cinnamon and cloves.
Next, peel, cut and slice the vegetables uniformly in size. Heat the vegetable oil to 350 in a skillet or dutch oven. I keep a cast iron dutch oven on my stove with canola oil because we cook french fries regularly. But use what you have to fry the potatoes in enough oil to cover the potatoes and cook the slices turning if necessary until golden brown. Remove to the paper towel lined casserole dish. Repeat until all the potatoes are cooked.
Brush the rimmed cookie sheet with a liberal amount of olive oil and rub the eggplant slices in the oil and then flip to coat the back side. Season with salt and pepper. Put in the preheated oven and cook until tender.
While the eggplant are cooking, make the bechamel. Heat the milk in a pot and keep warm. In another pot melt the butter and once melted, sprinkle in the flour a little at a time using a wire whisk. Keep stirring and adding flour until the mixture is dry and starts to pull away from the pot. You are cooking out the flour taste is what you are doing. Next, add the milk a little at a time while whisking continuously to avoid lumps. Once all the milk has been added and it is smooth, add salt and pepper to taste and remove from the heat. Now temper the egg yolks by adding a cup or so of bechamel to the egg yolks and whisk to combine and then add to the bechamel. It should be delicious. Taste it, it should have flavor, add more salt and pepper if it doesn’t. Then add a sprinkle of nutmeg.
Now, remove the paper towel from the casserole dish and arrange the potatoes in a single layer, overlapping is ok (why would more potatoes ever be bad?) Next add a layer of meat sauce. Make it a good thick layer, don’t skimp, you have enough. Cover the meat with Kasseri. Add the eggplant layer, then add the bechamel layer and top with the panko mixture if you are using it. Put in the oven and cook for about 45 minutes until the Moussaka is golden brown and the bechamel is set. Enjoy! Kali orexi!
Make ahead note:
After you put the Moussaka in the oven, take a look around at your pots and pans and take a page from my book. Do it in stages. Make the Kima one day during the week for a meal with spaghetti, make the bechamel the day before when you have time and then on the day you want to have it, all you have to do is the vegetables and assemble. Just remember to put something on top of the bechamel to keep it from getting a skin. And you can also assemble all the parts while they are cold, just assemble, bring to room temperature, or close to it before putting in the oven.