In large pot of boiling salted water, cook penne for 8 to 10 minutes or until tender but firm, adding peas in during the last 3-5 minutes of cooking. Drain and set aside, reserving ¼ cup (60 mL) cooking liquid.
Meanwhile, heat oil in large nonstick skillet set over medium-high heat; cook shrimp and garlic for 2 to 3 minutes or until shrimp starts to turn pink. Add pasta, peas, pesto and reserved cooking liquid; toss to combine. Season with chili flakes and pepper. Divide pasta among plates. Serve with lemon wedges.
Tip: Also delicious with scallops, crab or chicken instead of shrimp.