Sauté the onions, carrots and celery until tender. Add the garlic, thyme and rosemary and continue cooking until lightly caramelized. Remove the vegetables and set aside.
Drain excess blood and moisture from the lamb.
Heat 2 Tbsp. of olive oil in the rondeau and add the lamb. Sear the meat until the juices run clear, stirring frequently for even colouration. (This also can be done in a roasting pan in the oven with frequent stirring.)
Drain the fat and moisture purged from the meat and return to the pan.
Add the black beer and simmer until reduced by half.
Combine the vegetables, demi glace, peas and the lamb mixture. Stir to combine without mashing the peas.
Heat to a simmer and add the Blond Roux.
Season with salt and pepper, then simmer and stir for 2 minutes to thicken. Remove from the heat.
Assemble by placing 320 g. of lamb and vegetable mixture in a desired serving vessel or takeout container.
Pipe the Mashed Stilton Potatoes over the lamb-vegetable mix, using about 320 g. of potatoes. Set aside for service.
TO PREPARE À LA CARTE:
Heat the oven to 200°C and warm the desired number of portions for 15 minutes, or until they reach an internal temperature of 74°C.
To plate, place the shepherd’s pie on a serving plate and garnish with fresh thyme and rosemary.