1. Cook the Pasta:

1. In a large pot, bring the water to a rolling boil.
2. Add salt to the boiling water. The water should taste like the sea.
3. Add the dry penne pasta to the boiling water.
4. Stir a few times to prevent the pasta from sticking together.
5. Cook the pasta according to the package directions (usually about 10-12 minutes), or until al dente (firm to the bite).
6. Before draining, reserve about 1/2 cup of the starchy pasta water. This can be used to adjust the sauce consistency later.
7. Drain the pasta in a colander and set aside.

2. Sauté the Veggies:

1. Heat the butter (or olive oil) in a large saucepan over medium heat.
2. Add the minced garlic and sauté for about 30 seconds, or until fragrant. Be careful not to burn the garlic.
3. Add the diced bell pepper, broccoli florets, sweet corn and diced carrots.
4. Cook the vegetables for 2-3 minutes, or until they are tender-crisp (slightly softened but still have some crunch).
5. Season with a pinch of salt.
6. Turn off the heat and set the vegetables aside.

3. Make the White Sauce (Béchamel Sauce):

1. In the same saucepan (no need to wash it), melt the butter over low heat.
2. Add the all-purpose flour and stir continuously with a whisk until well combined and smooth, forming a paste called a roux.
3. Cook the roux for 1-2 minutes, stirring constantly, until it’s lightly golden and smells nutty. This step cooks out the raw flour taste. Do not let the roux brown.
4. Slowly pour in about 1/2 cup of the milk, whisking constantly to prevent lumps from forming.
5. Once the mixture is smooth, gradually add the remaining milk, whisking continuously.
6. Continue to cook the sauce over low heat, stirring constantly, for about 4-5 minutes, or until it begins to thicken and comes to a gentle simmer.
7. Stir in the heavy cream (if using), grated cheese, oregano, red chili flakes, black pepper, and salt.
8. Continue stirring until the cheese is melted and the sauce is smooth and creamy.
9. The sauce is done when it coats the back of a spoon. The sauce will thicken further as it cools.

4. Combine and Serve:

1. Add the sautéed vegetables and the cooked penne pasta to the white sauce.
2. Toss gently to coat the pasta and vegetables evenly with the sauce.
3. If the sauce is too thick, add a little bit of the reserved pasta water, 1 tablespoon at a time, until it reaches your desired consistency.
4. Transfer the pasta to a serving plate or individual bowls.
5. Sprinkle with extra grated cheese and red chili flakes, if desired.
6. Serve immediately.