Cook the ground beef in a pan over medium-high heat, breaking it apart constantly until no longer pink. Drain any fat.
1 pound lean ground beef
Add diced onion, minced garlic, cardamom, salt, black pepper, and cinnamon to the cooked ground beef. Reduce heat and sauté until onions are translucent. Set aside.
1/2 teaspoon cinnamon, 1/2 teaspoon cardamom, 3/4 teaspoon salt, 3/4 teaspoon black pepper, 3 cloves garlic, 1/2 yellow onion
In a medium saucepan, melt the unsalted butter. Whisk in the all-purpose flour, then gradually whisk in the 8 cups of milk. Cook, whisking constantly, until the sauce is smooth and thickened. Stir in the kosher salt, cinnamon, and black pepper. Remove from heat and let sit for 10 minutes.
1/2 teaspoon cinnamon, 1 cup unsalted butter, 1 cup all-purpose flour, 8 cups whole milk, 2 teaspoons kosher salt, 1 teaspoon freshly ground black pepper
Preheat the oven to 375 degrees Fahrenheit.
In a large bowl, combine the cooked penne pasta with 3 cups of the prepared béchamel sauce. Stir until the sauce coats all the pasta.
1 pound cooked penne pasta
Spread half of the penne mixture into a buttered 13x9-inch baking dish.
Spread the cooked ground beef mixture evenly over the penne layer.
Top with the remaining penne mixture.
Bake for 30-40 minutes, or until the top is golden brown. Keep an eye on it during the last 10 minutes to prevent burning.