Line an 8 x 8-inch square baking pan with aluminum foil. Butter foil lightly. Set prepared pan aside.
In a medium saucepan stir together sugar, evaporated milk and butter. Heat over medium-high heat until mixture comes to a rolling boil stirring constantly. Boil mixture, stirring constantly for 4 to 5 minutes. Reduce heat to medium if necessary.
Remove mixture from heat and stir in marshmallows, chocolate and mint chips, baking chips and peppermint extract. Stir vigorously until marshmallows and chips have melted.
Quickly pour mixture into prepared pan. Place pan in the refrigerator, uncovered for several hours before cutting.