1.) Cut each orange in half horizontally and juice on a juicer (don't squeeze by hand as you're saving the orange peels to use a potato cups and don't want them to get smashed). Reserve juice. Clean out each orange "cup." I used a grapefruit knife to clean out most of it then scraped out the rest with a spoon. It's ok if there is a bit of orange pulp left over - it adds flavor.
2.) Peel potatoes and cut into chunks. Boil in a large pot until potatoes start to fall apart. Strain. Mash or whip potatoes to desired consistency, adding splashes of reserved orange juice until potatoes are creamy (you won't use all the juice). Add butter, brown sugar, and salt to taste and mix well.
3.) Fill each orange cup with a "mountain" of potato mixture and place on a baking sheet. Bake in a 400 degree oven for about 10 minutes or until the potato peaks begin to brown.
4.) Remove and serve. Yum!