Cook the pasta until al dente. Reserve 1 cup of pasta water before draining.
Pat scallops dry and season with Cajun seasoning.
Sear scallops in hot olive oil, 90 seconds to 2 minutes per side, without crowding the pan. Remove immediately.
Cook bell pepper in butter for 3 to 4 minutes. Add garlic and cook 30 seconds.
Add stock, scraping up browned bits, and simmer 1 to 2 minutes.
Stir in cream and simmer 3 to 4 minutes to reduce slightly.
Stir in Parmesan until smooth.
Toss pasta into the sauce, loosening with pasta water as needed. Add scallops back, garnish with parsley, and serve with lemon wedges.