Place the fresh basil leaves, olive oil, and garlic cloves into the container of a high-speed blender or food processor. 2.
Blend until the mixture is a smooth purée. You may need to stop the machine and scrape down the sides with a spatula to ensure everything is incorporated. 3.
Pour the blended basil mixture into a small bowl.
Add the grated Parmesan cheese and the softened butter. 4.
Stir everything together by hand until the cheese and butter are fully combined. This is the secret to a perfectly smooth, non-gummy texture! 5. Use immediately, or store in the refrigerator in an airtight container for up to a week.
When saucing pasta, thin the pesto with a few tablespoons of the hot, starchy pasta water to create a perfectly silky coating.
