Wash, dry and prick potatoes with a fork. Bake in 400-degree oven for 1 hour or until done. Let cool. Cut into half lengthwise and scoop out pulp; set aside. Use skins for something else, such as stuffed potato skins.
Melt butter in heavy saucepan over low heat; add flour, stirring until smooth. Cook 1 minute, stirring constantly. Gradually add milk, cook over medium heat, stirring constantly until mixture is thickened and bubbly.
Add potato pulp, salt, pepper, 2 Tbsp. green onion, half the bacon and 1 cup cheese. Cook until thoroughly heated. Stir in sour cream. Add extra milk if necessary for desired consistency. Serve with remaining green onions, bacon and cheese.