Pierce 3 russet potatoes a few times with a fork. Bake on an oven rack at 350 degrees F until tender, 1 hour; let cool. Increase the oven temperature to 450 degrees F. Quarter the potatoes lengthwise and scoop out most of the flesh. Brush the potato wedges on both sides with melted butter; season with salt and pepper. Bake skin-side up on a baking sheet until crisp, 15 minutes. Flip, sprinkle with a mix of grated sharp cheddar and habanero cheese and bake until melted, 3 more minutes. Top with sour cream and chopped scallions.