Preheat oven to 375°F.
Pierce potato skins with a fork. Bake on a sheet tray until cooked through, about 45 minutes.
When potatoes are finished, remove them from the oven and increase heat to 425°F. Cut the potatoes in half lengthwise then use a spoon to scoop out the flesh into a mixing bowl.
Place the remaining potato skin “boats” back on the roasting tray and brush them with about 2 tablespoons of the melted butter. Season with salt and return them to the oven for 10-12 minutes or until they are crisp and slightly browned.
While the potatoes are baking, heat a sauté pan on medium-high. Add the oil and cook the Broccoli Cole Slaw until slightly wilted, about 3-4 minutes. Add the garlic for the last minute of cooking, stirring until fragrant. Season with salt and remove from heat.
Mash the potato flesh with a hand-held masher or food ricer. Add the cooked Broccoli Cole Slaw, remaining melted butter, sour cream, cheddar cheese, and Parmesan cheese. Mix well to combine, add more sour cream if necessary, and season with salt to taste.
Once the potatoes are done baking, use a spoon to fill the potato boats with the mixture and sprinkle with additional Parmesan cheese.
Return the potatoes to the oven for a final time, roasting for 10-12 minutes more or until cheese is golden brown on top.