Here is a goal: How do I prepare red bell pepper and spinach for goal cheese white sauce pasta?

Which way makes more sense to accomplish this goal?

Options are: a. Sice red bell pepper and saute in cast iron pan, also saute the spinach. To saute put cast iron pan over medium high heat and add some olive oil, cook peppers for 3-5 minutes and spinach until it wilts. b. Sice red bell pepper and saute in a trivet, also saute the spinach. To saute put cast iron pan over medium high heat and add some olive oil, cook peppers for 3-5 minutes and spinach until it wilts.
a.