Creamy Pesto Tortellini Pasta Salad

Name: Creamy Pesto Tortellini Pasta Salad
Ingredients: 20 ounce package three cheese refrigerated tortellini; 2/3 cup caesar salad dressing , divided; 1 1/2 cups cherry tomatoes , halved; 6 ounces black olives , drained and chopped; 3 green onions , chopped; 1/4 cup basil pesto ,homemade or store-bought; salt and freshly ground black pepper ,to taste; 1/4 teaspoon garlic powder; 1/3 cup sunflower seeds; 2/3 cup freshly grated parmesan cheese ,divided; 6-8 fresh basil leaves ,chopped, for garnish