For the red wine demi-glace sauce: Heat the olive oil in a 2-quart saucepan over medium heat. Saute the red onions and garlic until tender. Add the wine, beef base, pepper and 1 1/2 cups water. Bring to boil and reduce by one-third, about 10 minutes. Strain through a fine-mesh strainer into a clean pan. Heat over medium-low heat.
Mix the cornstarch with 3 ounces water to make a slurry. Whisk small amounts of the slurry into the sauce until the desired consistency is reached. Keep warm.
For the lamb-stuffed cabbage: Preheat the oven to 350 degrees F.
Remove the dark green outer leaves and the cores from the cabbages and wrap each head in plastic wrap with a little water. Microwave on high until softened, about 12 minutes. Separate the heads into individual leaves.
Combine the ground lamb, Cheddar, whiskey, wine, breadcrumbs, garlic, celery, eggs, red peppers, green peppers, shallots, onions, scallions, 2 tablespoons salt and 1/2 tablespoon pepper in a large bowl. Mix by hand until all ingredients are fully incorporated.
Stuff cabbage leaves with about 2 3/4 ounces of the lamb mixture; then roll the leaves around the filling. Place the rolls, seam-side down, in a large baking dish. Fill the pan halfway with water and drizzle the melted butter over the rolls. Cover with foil and bake until tender and very lightly browned, about 1 hour.
Spoon the demi-glace sauce over the cabbage rolls.
This recipe was provided by a chef, restaurant or culinary professional. It has not been tested for home use.