Melt butter in a medium saucepan over medium-high heat. Add bell pepper, onion, and celery. Saute, stirring frequently, until vegetables start to become translucent. Add garlic and saute about 1 minute more.
Meanwhile, in a large skillet, brown sausage rounds. Add vegetables to skillet and combine. Add rice and pasta sauce and mix well. Shake in a pinch of crushed red pepper, if desired.
Bring mixture to boil over medium-high heat. Lower to simmer, cover, and cook about 20 minutes, or until rice is thoroughly cooked and liquid is absorbed.