For the meatballs: Preheat the oven to 400 degrees F.
Heat a saute pan over medium to medium-high heat; melt
the butter. Add the onion, celery
and garlic; season with salt, pepper and thyme
. Cook to tender, 7 to 8 minutes. Deglaze
with the sherry
Soak the bread in milk while the veggies cool.
Place the meat in mixing bowl; season with salt and pepper. Squeeze the liquid out of the bread and crumble into the bowl. Add the cooked vegetables, parsley, Worcestershire, mustard and eggs
; combine to mix but do not overwork.
Place parchment paper on a baking sheet and roll the meat into 24 balls. Spray with cooking spray
about 15 to 18 minutes until lightly crispy and golden and cooked through. Cool and store for a make-ahead meal. Reheat, covered, in a preheated 375-degree F oven with a splash of water or they will stick in the bottom of the dish. Once meatballs are hot, uncover and crisp
up for 5 minutes.
For the mash: Fill a pot halfway with cold water. Peel
and add the potatoes as they are chopped or, if you peeled up the potatoes ahead, place in a pot and fill with fresh water. Add enough water to cover the potatoes, then cover the pot and place over high heat to bring to a boil. Once the water boils, remove the lid, salt the water and cook, uncovered, at a low boil until tender to fork. Drain
and return to hot pot
. Mash the potatoes with the sour cream and cream, a liberal dose of pepper, horseradish
; salt to your taste. If you wish to make the potatoes ahead of time and hold them for a couple of hours, place an inch of water in a large pot and bring to boil, then reduce heat to low and place a smaller pot, filled with the potatoes, into simmering water and cover that pot.
For the gravy: Melt the butter in saucepan
over medium-high heat. Whisk
in the flour and bring to a bubble; whisk in the stock and Worcestershire, season with pepper and thicken. Temper the egg yolk by lightly beating a ladle of gravy into it, then whisk into the sauce. Cool and store; reheat over medium heat, adding a little more stock, if necessary, to loosen.
Serve in shallow bowls. Spoon in enough potatoes to gently mound up in a bowl, then arrange a few meatballs in the center of the mound. Ladle gravy down over top and garnish