Cook the penne in a large saucepan of boiling water following packet directions or until al dente. Refresh under cold water. Drain well.
Meanwhile, heat the oil in a large frying pan over medium-high heat. Cook the prawns for 2 minutes on each side or until the prawns curl and change color. Transfer to a plate. Add the chorizo to the pan and cook, stirring, for 3 mins or until golden brown. Remove from heat.
Return the prawns to the pan with the penne, pesto, olive, and baby mozzarella balls. Season and toss to combine. Sprinkle with basil and serve.
Notes
TO STORE: Transfer leftover shrimp pesto pasta into an airtight container and refrigerate it for up to 4 days. Any longer and the pesto isn't as flavorful. TO FREEZE: Place the cooked and cooled pasta in a shallow container and store it in the freezer for up to 6 months. TO REHEAT: Microwave portions of the pasta for 20-30 seconds or reheat in a non-stick skillet until hot.