For the Lamb: Preheat the oven to 475 degrees F. Combine the crumbs, garlic, herbs, olive oil and mustard in a small bowl. Season with salt and pepper. Place the lamb on a rack in a baking pan. Season the lamb with salt and pepper to taste. Spread half of mustard mixture on inside of lamb. Roll and secure with string. Sear lamb on all sides and bake in the oven for 15-20 minutes, until lightly golden. Reduce the heat to 350 degrees, remove the lamb and spread the remaining 1/2 of mustard mixture evenly over the top. Return to the oven and continue roasting until medium rare, about 1 1/4 hours. Let rest 10 minutes and slice thinly on the bias.
For the Bean Ragout: Heat olive oil in a medium saucepan over medium heat. Add shallots, carrots and celery and sweat for 5 to 7 minutes. Increase heat to high and add the cooking liquids and chicken stock. Cook until reduced to 2 cups and strain. Place the beans and artichokes in the saucepan and add the stock. Cook until the liquid has reduced to 1/4 cup. Add the butter, thyme and parsley and season with salt and pepper to taste. Spoon the mixture onto a platter and top with the pancetta and tomatoes.