Preheat oven to 450°. Cut 4 bananas into 2-inch pieces; halve each piece lengthwise. Mash remaining bananas to equal 1/2 cup. Sift together flour and next 4 ingredients in a large bowl; add mashed bananas and peanuts. Grate butter over flour mixture, using large holes of a box grater. Cut butter into flour mixture with a pastry blender or fork until crumbly. Add buttermilk, stirring just until mixture is slightly moistened.
Turn dough out onto a heavily floured surface; shape into a ball. Pat into a 1/2-inch-thick circle.
Cut with a floured, 3-inch round cutter, and place biscuits 1 inch apart on a lightly greased baking sheet.
Bake at 450° for 10 to 12 minutes or until golden. Split warm biscuits; spread bottom halves of biscuits with Peanut Butter Spread. Top each with 2 bacon pieces and 2 banana slices. Cover with biscuit tops.