Prepare the gluten-free pasta, per the directions on the box. Set aside.
In a rimmed baking sheet, toss the tomatoes, bell pepper and onion with olive oil.
Sprinkle mixture with garlic salt.
Roast tomato mixture at 400 degrees F for 15 minutes.
Remove from oven and let rest for 10 minutes.
Place tomato mixture into blender. Blend until smooth.
Toss sauce with cooked pasta, olives and capers.
Garnish with fresh parsley.