Heat oil in a nonstick skillet coated with cooking spray over medium heat. Add red bell pepper and garlic; cook, uncovered, 30 minutes, stirring occasionally. Set aside, and cool slightly.
Place pepper mixture in a blender; add chopped basil and next 3 ingredients. Process until smooth, stopping once to scrape down sides.
Cook pasta according to package directions, omitting salt and fat.
To serve, top pasta with pepper sauce. Garnish with basil sprigs, if desired.