Creamy Pesto Tortellini Pasta Salad

package three cheese refrigerated tortellini

creamy caesar dressing (,divided)

cherry tomatoes (,halved)

can black olives (drained and chopped)

green onions (,chopped)

basil pesto (,homemade or store-bought)

salt and pepper (,to taste)

garlic powder

sunflower seeds

fresh grated parmesan cheese (,divided)

fresh basil leaves (,chopped, for garnish)