Preheat the oven to 400°F. Place the quartered potatoes onto a sheet pan. Drizzle with enough olive oil to coat the potatoes well. Sprinkle a good pinch of salt and the spice blend over top. Use your hands to toss well.
Spread the potatoes out onto the sheet pan in one even layer, flat-sides facing down. Roast for 1 hour.
When the potatoes have about 20 minutes left, pour the apple cider vinegar into a small saucepan. Place over medium-high heat and bring to a simmer. Lower the heat to medium-low and reduce the vinegar for about 12 minutes. Add the honey. Simmer for a few minutes longer. Turn off the heat and whisk in the butter, one tablespoon at a time.
Transfer the potatoes to a large mixing bowl. Pour most of the glaze into the bowl and toss well. Spread the mascarpone cheese onto a large platter as a base. Mound the potatoes on top of the cheese. Drizzle any extra glaze over top.