Use a cookie cutter to cut circles from each slice of Cinnamon-Sugar Swirl Potato Bread. (Tip: save the scraps to make bread pudding casserole or cinnamon-sugar croutons!)
Add the softened butter, marshmallow fluff, powdered sugar, vanilla, and salt to a large mixing bowl and beat with a hand mixer until creamy and fluffy. If the filling is too stiff, add a bit of heavy cream or milk and beat to combine.
Assemble whoopee pies by spreading or piping filling onto half the swirl bread circles. Sandwich with remaining bread slices, pressing down slightly so that the filling spreads to the edge.
Keep refrigerated until ready to serve.
Tip: Serve with our Classic Mocha recipe for a fun cozy meal pairing!