How about cake?!
Seriously, I dont know exactly what you want from a breakfast, but my Mum is losing weight and wanted a tasty, yet low carb meal to satisfy her.
I developed protein cake which she makes in a mug every morning, takes 2 mins.... but I supose you could match bake it
One egg, in a mug with one 30g scoop of whatever protein flavour you like, microwave for a minute or so will make a cake alternative.
However this will be a little dry, I prefer to go 50% protein powder, and 50% almond flour. By increase teh fat content you make the cake less dry.
Feel free to add cocoa, sweetener, a mashed banana or whatever! The principle is always one egg plus flour replacement in a mug heres one I amde earlier: