⅓cupfreshly squeezed lemon juice, from about 2 lemons, use the same ones you just zested
12ouncespenne pasta (see note)
2-3cupschopped fresh broccoli florets
½cupfreshly grated Parmesan cheese
Pat the chicken dry with a paper towel and season well with salt and pepper. Heat the oil in a large, 12-inch nonstick skillet over medium heat until the oil is hot and rippling. Add the chicken and saute, stirring frequently, until the chicken is browned and cooked through. Remove the chicken to a plate, keeping as much oil/liquid in the skillet as possible.
Keep the skillet on medium heat and add another teaspoon of oil if needed (I usually don't but you'll want to keep an especially close eye on the garlic). Add the garlic and basil and stir constantly for about 30 seconds. Add the water, broth, lemon juice and pasta. Stir to combine.
Bring the mixture to a simmer and cook, stirring occasionally just to keep the pasta from sticking, for 10-12 minutes until the pasta is tender - it will cook for a few more minutes in the next step. There will be a bit of liquid left in the skillet; that's ok.
Add the broccoli and lemon zest. Cover and cook for 2-3 minutes until the broccoli is bright green and tender. While the broccoli is cooking, whisk together the milk and cornstarch.
Uncover the skillet and stir in the milk mixture along with the Parmesan cheese and reserved chicken. Simmer, uncovered, until the sauce has thickened slightly, 1-2 minutes.
Season with additional salt and pepper (this is really important - don't skip this step!) and serve.
Penne: the brand of penne you use will define how much liquid to add total. When I use the Creamette (green package) brand of penne that cooks to al dente in 7 or so minutes, I use the amounts stated in the recipe. But I've also made this with Barilla penne which is slightly thicker and needs 10-11 minutes to cook until al dente. When using a pasta like that (thicker with more cooking time needed), keep your eye on the liquid amount. If the liquid is mostly absorbed but the pasta isn't close to being tender yet, add another 1/2 cup liquid to the skillet (and possibly another minute or so of cooking time).Lemon: if you want to give a burst of fresh lemon flavor, squeeze an additional 1 tablespoon of fresh lemon juice into the skillet pasta right before serving.Skillet/Pot:also, if you don't have a large 12-inch skillet, you could totally make this in a large pot. Sauce: finally, if you like your sauce a bit thicker, use a little extra cornstarch (maybe another 1/2 tablespoon?) or cover the skillet off the heat and let the pasta sit for 5-10 minutes before serving.