Step 1: The Al Dente Boil

1. Boil the **penne** in heavily salted water. Crucial: Drain the pasta 2 minutes *before* the package instructions say it’s done.
2. The pasta will absorb the Béchamel sauce in the oven; if it’s already fully cooked, it will become mushy.

Step 2: Crafting the Roux

1. In a heavy-bottomed saucepan over medium heat, melt the **butter**.
2. Whisk in the **flour** and cook for 1–2 minutes. You want a “Blond Roux”—it should smell slightly nutty but not turn brown. This step is essential to cook out the “raw flour” taste.

Step 3: The Liquid Emulsion

1. Gradually pour in the **milk** and **heavy cream**, one splash at a time.
2. The Whisking Secret: Whisk vigorously after each addition until the liquid is fully incorporated before adding more. This ensures a silk-smooth sauce with zero lumps.
3. Simmer until the sauce is thick enough to coat the back of a spoon.

Step 4: The Cheesy Transformation

1. Remove from heat. Add the **salt, pepper**, and **half of the cheese blend**.
2. Stir until the cheese has completely melted into the sauce. Fold in the cooked pasta until every tube of penne is filled with sauce.

Step 5: The Final Bake

1. Preheat your oven to **200°C (390°F)**.
2. Transfer the mixture to a buttered baking dish. Top with the **remaining cheese**.
3. Bake for **15 minutes**. For a perfect finish, turn on the **Broiler (Grill)** for the last 2 minutes to get those crispy, dark-golden cheese spots.