In a small mixing bowl, combine the dried basil, dried parsley, garlic powder, onion powder, dried oregano, salt, black pepper, dried thyme, dried mustard powder, and red pepper flakes (if using). Mix well until all the ingredients are evenly distributed.
Transfer the mixture to an airtight container, such as a small jar, and store it in a cool, dry place until ready to use.
To make Caesar dressing, whisk together 1 tablespoon of the seasoning with 1/2 cup of mayonnaise, 1/4 cup of grated Parmesan cheese, 2 tablespoons of lemon juice, and 1 tablespoon of Dijon mustard in a small bowl.
Slowly whisk in 1/4 cup of extra virgin olive oil until the dressing is emulsified.
Serve the Caesar dressing with a crisp salad of romaine lettuce, homemade croutons, and additional grated Parmesan cheese.