Penne with Herb Butter and Peas

1 stick unsalted butter, softened
1/4 cup finely chopped fresh herbs of your choice (I used chives and mint in mine) Kosher or sea salt to taste Kosher salt
3/4 cups freshly shelled English peas
1/2 pound penne rigate Herb butter

For the herb butter: In a small bowl, mash the butter with the herbs and a couple large pinches of salt.
Mound the butter onto a piece of plastic wrap and gently roll it up like a cigar, forming the butter into a cylinder as best you can. Twist the ends of the plastic to create a more compact and neat cylinder, and fold the ends under. Refrigerate the butter until firm enough to slice. (This will keep for weeks in your fridge or freezer.)
For the penne: Bring a large pot of generously salted water to a boil. Dump in the peas and cook them for a couple of minutes, until they're bright green and just tender. Remove them with a slotted spoon and put them into a colander; run some cold water over the peas to stop the cooking.
Bring the water back to a boil and add the penne. Cook until just al dente, following the instructions on the package. Reserve a cup of the cooking water before you drain the cooked pasta.
Working quickly, return the pot to the stove over medium low heat and add 3 tablespoons of the herb butter. Once it starts to melt, add the pasta and peas. Fold it all together gently, coating everything in the herb butter. Add some of the cooking water if the pasta seems dry. Serve immediately, while the peas and herbs are still bright green!