This works best with filet steak, however I have also made it with thick cut sirloin & it was yummy. It's nice as a special treat or dinner. I think this is an Annabel Langbein (NZ Chef) recipe but with a definite French influence.
Pulse the bread in a food processor until the crumbs are coarse (you don't want them really fine).
Put the melted butter into a small bowl, and add the garlic, thyme and fresh breadcrumbs. Stir until well combined.
Heat a frypan onto high heat & add the olive oil. The pan should be smoking.
While the pan is heating, trim any excess fat and silverskin from the steaks, and grind black pepper to taste over the steaks.
Using tongs (and watch for spatters) put the steaks into the pan and quickly sear on all sides.
Remove to an oven tray and spread with Dijon Mustard to taste.
Pile the crumb mixture on top in an even layer, and put into the oven until cooked to your liking (I like this rare, so about 15 minutes or so at most for me is fine). Ensure that the crumb doesn't burn (but it should be golden).