Preheat oven to 400 F. Bring a large pot of salted water to boil. Grease a 9-by-13-inch baking dish.

Add macaroni to boiling water and stir to prevent sticking. When there are 4 minutes remaining on the cooking time, add the broccoli and continue cooking for 2 minutes longer, then drain. The broccoli should be bright green and crisp-tender and the pasta slightly undercooked. Return pasta and broccoli to the pot and toss with 2 tablespoons of butter or ghee until evenly coated. Set aside.

While the pasta cooks, melt 1 tablespoon of butter or ghee in a large skillet over medium-high heat. Add the diced onion, and cook until softened and just starting to brown, about 3 minutes. Add the ground meat and break it up into smaller pieces as it cooks. Continue cooking until the meat is no longer pink, 6 to 8 minutes. Add the ground meat to the pot with pasta and broccoli.

Wipe out the skillet and melt the remaining 2 tablespoons of butter or ghee over medium heat. Add the flour and stir constantly until the mixture is lightly browned, 1 to 2 minutes. Add the milk, whisk to remove lumps and add salt and pepper. Cook over medium-high heat, stirring constantly, until the sauce thickens and starts to bubble, about 6 minutes. Remove from heat, stir in the cheese and whisk until melted and smooth.

Add the cheese sauce to the pot with pasta and stir until evenly combined. Pour the cheesy pasta mixture into the prepared baking dish and bake for 35 to 45 minutes, until the top is browned and bubbly.

Top with fresh herbs (optional), freshly cracked black pepper and salt to taste.