HEAT oven to 400°F.
TOSS squash and red peppers with 2 Tbsp. dressing; spread onto baking sheet.
BAKE 20 to 25 min. or until crisp-tender; cool.
MIX mayo and remaining dressing in large bowl. Add pasta, roasted vegetables, 1/2 cup basil and seasonings; mix lightly. Top with remaining basil.