Bring a large pot of salted water to a rolling boil and cook your penne according to the package directions until al dente. Right before draining, scoop out about half a cup of the starchy pasta water and set it aside. This water is liquid gold for the sauce later, so don't skip it.
While the pasta cooks, dice your cooked chicken into bite-sized pieces so every forkful gets some protein. Cut the zucchini into thin matchsticks rather than rounds, since the thinner shape cooks faster and mimics the texture of the pasta strands.
Drain the pasta and return it to the same warm pot. Add the diced chicken and zucchini matchsticks straight in, then toss everything together. The residual heat from the pasta will start softening the zucchini slightly, which is exactly what you want.
Add the cubed, chilled brie directly to the warm pasta mixture and stir gently. The heat will start melting the cheese into a creamy coating almost immediately, rind and all if you like that slightly earthy flavor.
If the sauce looks too thick or clumpy, splash in a bit of the reserved pasta water and stir. Keep adding a tablespoon at a time until the cheese turns glossy and coats every piece of pasta evenly.
Stir in the chopped fresh basil and season with salt and pepper to taste. Give it one last toss, then serve immediately while the sauce is at its silkiest.