1. In a large pot, bring 1 gallon water to a boil over high heat. When water boils, sprinkle in 4 tsp. salt, then add penne. Stir pasta well and cook about 12 minutes, stirring once or twice, until just tender, or al dente.
2. Meanwhile, heat oil in a large skillet over medium heat. Add garlic and cook 1 minute, being careful not to burn it. Add walnuts and cook, stirring, for 2 minutes. Add peas and cook another minute. Add cream, salt, and pepper and let simmer for about 3 to 4 minutes, or until slightly thickened.
3. Drain pasta, reserving 1/4 cup of the cooking water. Place arugula into pasta pot and top it with cooked pasta. Pour walnut sauce over pasta and toss well. Arugula will 'melt' from the heat of the sauce and pasta. If desired, thin sauce with reserved pasta water. Serve immediately.
Source: Hannaford fresh Magazine, January - February 2008