Cook Pasta according to instructions and when it is done turn off the heat and add the peas. Drain in 3 minutes and run under cold water. Put in a bowl
Noodles should be cool...Add chopped onions, green peppers, and shredded cheddar and set in fridge.
Add red pepper, garlic powder, ground mustard, and parsley to parmesan cheese and stir till it is mixed. Add mayonnaise to this mixture and then add buttermilk. Make sure the buttermilk, mayo, and dry ingredients are combined.
Pour over noodles and vegetables, combine well and chill for 1 hour.