Combine 4 quarts water, 2 tablespoons salt, and the potatoes in a large pot. Bring to a boil and cook until the potatoes are fork tender, about 20 minutes. Drain the potatoes, add back to the hot pot, and cook, stirring, until the potatoes stop steaming.

Preheat the oven to 400°F. Grease a Dutch oven or 9x12-inch baking dish with butter.

Mash the potatoes with 10 tablespoons butter, sour cream, eggs, 1 teaspoon salt, and pepper. Stir in the chives. Spread the potatoes in the prepared Dutch oven. Can be made ahead and refrigerated, covered, up to this point. When ready to bake, let sit at room temperature while the oven preheats.

Melt 4 tablespoons butter and combine with the bread crumbs and cheese. Sprinkle the mixture over the top and bake for 30-40 minutes or until golden brown.