01 -
In a large pot, heat olive oil over medium heat. Add chopped onions, sprinkle with salt, and cook until translucent. Add ground beef and cook until no longer pink, breaking up with a wooden spoon. Stir in tomato sauce and cinnamon, and bring to a simmer. Season with salt to taste. Let stew with a lid slightly askew, stirring occasionally, for 3 hours. Cool and refrigerate overnight.
02 -
Cook noodles in boiling salted water until al dente, reducing the time by 1–2 minutes from package directions. Drain and cool. Toss noodles with one beaten egg in a large bowl using hands.
03 -
Preheat oven to 350°F. Lightly coat a lasagna pan with olive oil or nonstick spray. Evenly arrange noodles in the bottom of the pan. Sprinkle with one-third of grated cheese. Using a slotted spoon, distribute meat mixture evenly over the noodles and cheese layer. Sprinkle another one-third of grated cheese over the meat layer.
04 -
In a heavy-bottomed pot, melt 1 stick of butter. Add flour and whisk until combined. Cook while stirring for 1–2 minutes. Gradually whisk in 5 cups of milk, cooking until bubbling and thickened. Beat 3 eggs and ½ cup milk in a separate bowl, then slowly whisk into the pot. Continue cooking until thickened. Let rest for a few minutes off heat.
05 -
Pour prepared béchamel over the meat and cheese layer, spreading evenly. Top with the remaining grated cheese. Melt ½ stick of butter and drizzle over the top.
06 -
Place the pan on a baking sheet and bake for 1 hour, or until the top is browned and the center is hot. If additional browning is needed, use the broiler for 3–5 minutes, monitoring closely. Let rest for 10 minutes before serving.