Preheat the oven to 500 degrees F.
Bring 5 quarts of salted water to a boil in a stockpot.
Combine all the ingredients except the penne and butter in a large mixing bowl. Mix well.
Drop the penne into the boiling water and parboil for 4 minutes. Drain well in a colander and add to the ingredients in the mixing bowl, tossing to combine.
Divide the pasta mixture among 6 shallow ceramic gratin dishes (1 1/2 to 2-cup capacity). Dot with the butter and bake until bubbly and brown on top, 7 to 10 minutes.
