Twice baked mash potatoes

Put 4 Russett potatoes in oven at 375 degrees for 1 hour.  When done, scoop out potatoes from their skins.  Warm milk and butter in microwave.  In bowl put milk and butter.  Mash.  Still at 375 degrees put in oven for 15 minutes.  Then top with cheddar cheese and if you like green onions.  Turn down heat.  Leave in just long enough to let cheese melt.          From 10 Dollar Dinners-Food Network