The website where I found this copycat recipe also has another recipe for this dressing, which I have a feeling probably tastes a bit more like the original -- but it contains raw egg, which my pregnant self can't have right now.
This truly is a very good salad dressing, as long as you don't have expectations that it's going to taste like the original. For my part, when I'm craving Olive Garden's dressing, I'm just going to go to the restaurant across the street from where I work and buy a bottle of it.
"Olive Garden Salad Dressing"
Source: Group Recipes
1/2 cup mayonnaise
1/3 cup white vinegar
1 teaspoon vegetable oil
2 tablespoons corn syrup (I used sugar)
2 tablespoons Parmesan cheese
2 tablespoons Romano cheese
1/4 teaspoon garlic salt (or 1 garlic clove, minced)
1/2 teaspoon Italian seasoning
1/2 teaspoon parsley flakes
1 tablespoon lemon juice
Mix all ingredients in a blender or food processor until well-combined. Serve over salad.