Combine all pesto ingredients in a food processor and blend until smooth. Add salt and pepper to taste and transfer pesto to a bowl.
Toast almonds in a non-sticking frying pan for 2-3 minutes until lightly golden, then reserve.
In the meantime, cook the tortellini according to package instructions and drain, reserving a ladleful of the pasta cooking water. Add pasta to the pan and stir gently, adding some of the pasta water if you need to loosen the sauce.
Sprinkle with toasted almonds and serve.