Urgent! A question about a recipe: Summer Squash Gratin with Salsa Verde and Gruyere

I have a question about step 1 on the recipe "Summer Squash Gratin with Salsa Verde and Gruyere" from amanda. It says:

"Make the salsa verde. Using a mortar and pestle (or a food processor, I won't tell anyone), pound the herbs to a paste. You may have to do this in batches. Work in some of the olive oil, and transfer the mixture to a bowl. Pound the garlic and anchovy, and add them to the herbs." Can I substitute anchovy paste for the anchovy in the Salsa Verde?