Prepare an ice bath to blanch the basil leaves. Fill a large bowl about a quarter of the way with ice cubes then add cold water until the bowl is about 80% full. Store in the freezer (or refrigerator) until it's time to blanch the basil.

Fill a medium pot with water and heat until small bubbles start to appear on the bottom of the pan. Immediately reduce the heat to low to keep the water hot (but not boiling). The temperature should be around 210-220°F.

Submerge the basil leaves in the hot water for 45 seconds to a minute until the basil has a vibrant green color. Use a sieve or a spatula to keep all the leaves submerged so they heat up evenly.

Strain the basil leaves from the water by pouring the hot water/basil mixture into a fine-meshed sieve over a sink. Immediately submerge the basil (still in the sieve) in the ice bath prepared earlier. Move the basil around in the sieve so all the leaves cool.

Once the basil leaves are cold to the touch remove the sieve from the ice bath and squeeze the leaves in your fist to release all the excess water.

Add the drained basil leaves, pine nuts, parmesan cheese, pecorino romano cheese, olive oil, garlic, salt and 2 of the ice cubes to a high-powered blender. Puree for 2-3 minutes until the mixture forms a paste. The basil pesto won't be smooth at this stage. That is fine.

Stop the blender to scrape down the sides, pushing any contents along the sides towards the bottom blade to ensure all the pesto is completely smooth.

Add another ice cube to the blender and blend for an additional 2-3 minutes until the pesto is completely smooth with a bright green color.

Use immediately or store in the refrigerator in an airtight container for up to 7 days.