In a small pan, cook leek and celery gently with 2 Tbs of olive oil, adding 1 Tbs of water every now and then to cook without browning.
After sautéeing for about 10 minutes, season with salt and pepper and set aside.
Bring a large pot of water to boil and cook pasta according to package directions. After 3 minutes, add broccoli florets and cook together with the pasta.
Once penne is cooked al dente, drain pasta and broccoli, reserving 1/2 cup of the cooking water.
Add pasta and broccoli to the pan with the sautéed leek mixture, adding a little of the cooking water and remaining olive oil. Top with parsley.
