Cook the Pasta: Bring a large pot of salted water to a boil, add cavatappi pasta, and cook until al dente, about 7-9 minutes. Drain and rinse under cold water.

Brown the Beef: Heat olive oil in a large skillet over medium heat. Add ground beef and cook until browned, about 8-10 minutes. Drain excess grease.

Prepare the Vegetables: Chop red onion, diced dill pickles, green leaf lettuce, and halve cherry tomatoes if using.

Combine the Ingredients: In a mixing bowl, combine cooled pasta, browned beef, chopped vegetables, and cheddar cheese.

Add Dressing and Toss: Pour Thousand Island dressing over the mixture and toss gently until evenly coated.

Chill and Serve: Cover and refrigerate for at least 4 hours to meld flavors. Serve cold, sprinkled with sesame seeds.