Add the anchovies into a bowl along with the lemon juice, egg yolk, mustard, grated garlic, salt, pepper, and parmesan.
2 tbsp lemon juice, 1 egg yolk, 2 anchovy fillets, 1½ tbsp dijon mustard, 1 clove grated garlic, 1 pinch salt & pepper, ¼ cup grated parmesan