Cook spaghetti according to package directions. Reserve about 1 1/2 cups (375 mL) cooking water before draining.

Meanwhile, combine parsley, basil, olives, red onion, lemon juice, garlic, salt and pepper in a food processor. Pulse until finely chopped; pulse in 2 tbsp (30 mL) oil until smooth. Adjust seasonings to taste.

Heat remaining oil in a large skillet set over medium-high heat. Stir-fry shrimp and red pepper until shrimp are just opaque. Add spaghetti and pesto mixture. Toss in reserved cooking water, at little at a time, until pasta is moistened to taste. Serve immediately.