Place all ingredients except olive oil in food processor.
Turn the food processor on and drizzle olive oil through feed tube. If you need more to get the right consistency, use more.
Store in airtight container for up to 1 month.
In a large pot, bring water to a boil, then cook pasta according to instructions on box.
Once pasta is done cooking, drain well but reserving 1/4 cup of pasta water.
In the same pot, pour the pasta back in and add the 3 tbsp. of arugula pesto. The heat of the pasta will spread the pesto all over. Add in a little bit of the pasta water to thin it out. You might not need the full 1/4 cup.
Crumble goat cheese on top and stir well to melt and combine.