Bring a large pot of salted water to boil over medium to high heat and cook the spaghetti according to the package directions. Before draining, reserve 1 cup of the pasta cooking water.

Heat the olive oil and the butter in a large skillet over medium heat and when the butter is bubbling, reduce the heat to low and sautee the garlic for 1-2 minutes or until nearly golden brown.

Add the red pepper flakes and saturee for a few seconds. Add the drained spaghetti to teh skillet along with the arugula, parsley, and about 3/4 cup of the reserved water from the pasta water. Mix well.

Add the parmesan and toss util well mixed and heated through. Add a little more pasta water or olive oil if the pasta seems dry. Season to taste with salt and pepper and serve with more grated parmesan cheese on the side.