We made this recently. It is true comfort food. The hatch pepper is my own addition, it can be made without it. The cinnamon is necessary for the right flavor though.
Moussaka
1 lb ground beef 1 tsp paprika 1 cup diced onion 1/8 cup hatch pepper 1-2 Tbs tomato paste 1-2 cloves garlic, ½ can diced tomatoes
2-3 pinches cinnamon,1/2 tsp oregano, salt/pepper
2-3 small potatoes 1-2 med eggplants
For roasting eggplant and potatoes: olive oil,1-2 sprigs thyme salt/ pepper

Bechamel:1/4 cup butter, 1/4 cup flour, 2 cups milk ½ cup mozzarella ½ cup parmesan dash nutmeg Salt/ white pepper 2 beaten eggs

Brown beef and drain grease in colander. Slice and salt eggplant for 15 minutes, rinse and dry, slice potatoes ¼ in thick toss both in oil and thyme. Roast in 350deg oven for 20 mins in single layer on parchment paper. Saute onion and pepper in oil till softened, then add garlic for a couple mins. Add tomato paste and saute briefly, return beef to pan with diced tomatoes and spices, salt, and pepper. Mix and set aside.
In nonstick pan saute flour in butter, Add warmed milk while whisking with silicon whisk, Bring to simmer and add mozzarella. Whisk till smooth. Remove from heat and add parmesan, nutmeg , salt and pepper to taste. Allow to cool slightly, temper and whisk in eggs.
Arrange in oiled casserole,(I used a full size large pie dish) 1 layer of ½ the eggplant ,all the beef then a layer of potatoes, then remaining eggplant. Top with béchamel and bake at 350 degrees for 45 min to 1 hour.
Hatch pepper can be increased or decreased depending on heat level desired.