In a bowl, stir together cream cheese, Russian dressing, sauerkraut, Worcestershire sauce, and horseradish until well combined. Fold in Swiss cheese and corned beef. Season to taste with salt.

Preheat oven to 375 degrees F.

Slice 1 inch off of the top of the boule. Hollow out the inside of the bread, leaving a ½-inch border on the sides and bottom. Save the removed boule top and interior, cutting the bread into 1-½ inch-cubes to serve with the dip.

Place the bread bowl on a baking sheet lined with parchment or foil. Spoon the dip into the bowl, spreading it into the corners. If desired, sprinkle the top with a little bit of extra cheese (don't totally cover it so that the top of the dip can brown.)

Bake for 25-30 minutes, until the dip is heated through and the edges of the bread bowl are crispy.

To make the dippers, combine melted butter with garlic powder in a small bowl. Lightly brush the bread pieces with the garlic butter and sprinkle with kosher or sea salt. Add them to the baking sheet during the last 8-10 minutes that the dip is in the oven, until toasted.

Preheat oven to 350 degrees F.

Lightly coat a small, 1-quart baking pan, gratin dish, or skillet with cooking spray. Spread the dip into the prepared pan in an even layer.

Bake until warmed through and bubbling around the edges, 15-25 minutes, depending on the dimensions and material of your pan. (Wider, shallower baking dishes and cast iron tend to cook more quickly.) Start checking the dip on the early side of the time range so it doesn't overheat (which would cause the oils in the cheese to separate).

Let the dip stand for 3-5 minutes after coming out of the oven. Garnish with parsley and serve hot with bread dippers and/or your favorite crackers.