Place the ingredients for the pesto in the bowl of a food processor.
Pulse until the pesto is the consistency you prefer.
Add a splash of oil or more oil if you want the pesto to be a little looser.
Taste and adjust seasoning if needed then transfer to an airtight container or jar.
Add a few tablespoons of olive oil to the top of the pesto then store in the fridge until ready to serve. You can store the pesto up to 2 weeks in the refrigerator.
Heat a large pot of salted water over high heat.
Add the pasta and cook until al dente.
Reserve one cup of cooking water then drain the pasta.
Toss the pasta with the spinach pesto and a splash of cooking water. If you want the pesto sauce to be creamier, add a splash of heavy cream.
While the pasta is cooking, prepare the chicken.
Slice the chicken into bite-size chunks and place in a medium bowl.
Add oil, lemon juice, paprika, oregano, salt and pepper then mix well.
Heat a large pan over medium-high heat then add the chicken and cook until golden brown and cooked through.
Add the butter and garlic and cook for another 2 minutes.
Serve the pesto pasta with the chicken and fresh basil or arugula.