Whisk room temperature egg yolk with whisk or blender on low speed.
Add apple cider vinegar, mustard, lemon juice, garlic, Worcestershire sauce, and anchovy paste and Parmesan cheese if using, and blend until creamy.
Slowly add olive oil, whisking or blending constantly on low speed until incorporated.
Season to taste.
This recipe is definitely best right after it is made, but may be stored in an airtight container in the refrigerator for up to one week.If the dressing doesn’t incorporate well, your egg might still have been too cold! If needed, let sit at room temperature another 10 minutes, and whisk or blend again.