BEEF PASTITSIO

Steps:

• Preheat oven to 375 degrees. Heat oil in a medium saucepan or Dutch oven over medium-high. Add onion and garlic; cook, stirring occasionally, until softened, 4 to 5 minutes. Add beef and cook, breaking up the meat with a wooden spoon, until cooked through and browned, 6 to 8 minutes. Add tomato paste, oregano, cinnamon, 2 teaspoons salt, and 1/2 teaspoon pepper; cook, stirring until fragrant, 1 to 2 minutes. Add pureed tomatoes; bring to a boil, then reduce to a simmer and cook, partially covered, until thickened slightly, about 15 minutes.
• Meanwhile, bring a large pot of generously salted water to a boil. Add pasta and cook until just al-dente, about 2 minutes less than box instructions. Drain; set aside.
• Melt butter in a medium saucepan over medium heat. Add flour and cook, stirring constantly, until lightly golden and beginning to smell nutty, about 2 minutes. Gradually add milk, then cook, stirring constantly, until mixture comes to a boil. Remove from heat; whisk in nutmeg, 1/2 teaspoon salt, and 1/4 teaspoon pepper. Let cool slightly, about 10 minutes. Stir in egg yolk to combine.
• Arrange pasta in an even layer in bottom of dish. Spoon meat sauce over pasta. Spoon béchamel over meat sauce; sprinkle evenly with cheese. Bake until top is golden and set, and mixture is bubbling in the center, about 45 minutes. Let stand at least 30 minutes before serving.