Preheat oven to 200°C/390°F (all oven types). Place shelf in the middle of the oven.
Sprinkle lamb rack with salt and pepper, sear in Olive Oil on all sides, let cool for 5 minutes.
Mix dijon, rosemary, and garlic in a small bowl. Then add 3 teaspoons of egg, and mix again.
Mix Crumb ingredients EXCEPT butter in a bowl. Then use a fork to stir through butter. Spread on a dinner plate (large enough that fits lamb).
Spread the underside of the rack with mustard mix. Press into breadcrumb mixture, then spread mustard mix over the other side as well as each end. Then press those sides into the breadcrumb mixture.
Transfer lamb to rack set on a tray. Surround with parboiled vegetables if using - but don't crowd the lamb. Roast for 20 minutes until it registers 47 C (for rare).
Transfer lamb to a cutting board, loosely cover with foil. Rest 5 minutes then slice carefully using your hands to hold the crumb gently in place where you are cutting into 2-3 bone pieces using a very sharp knife.
Sauce
Boil wine and chicken stock together until reduced by 3/4, then whisk in cream and mustard and simmer for 3 - 5 minutes until thickened. The consistency should be a thin pouring sauce. We don't want to coat the lamb too thickly as the sauce flavor will be overpowering.