Heat a frying pan over medium heat. Add butter and let melt.
Add panko breadcrumbs to the pan and toast, stirring frequently, for about 2 minutes until golden.
Stir in the crushed Calabrian chili and continue to toast until fragrant and golden brown. Remove from heat and set aside.
Wipe out the pan and increase heat to medium-high. Add a drizzle of olive oil.
Once the oil is hot, add the calamari and cook for 3 minutes, stirring occasionally. You should hear a sizzle; if not, remove it and let the oil heat more.
Add the chili breadcrumbs and a pinch of salt. Cook for another 1-2 minutes until the calamari is tender but not chewy. Remove from heat.
Plate the calamari and garnish with finely chopped parsley. Serve immediately.
Notes
Storage: Calamari turns rubbery fast, so this is really a cook-and-eat-right-away dish. If you do have leftovers, reheat gently in a hot pan rather than the microwave, and expect it to lose some of its bite.