Nan's Peanut Butter Fudge with Marshmallows

Butter an 8-inch square pan.

Combine sugar, evaporated milk, and butter in an electric skillet. Set control to 260 degrees F (120 degrees C).

Bring to a boil and boil 5 minutes, stirring constantly. Turn off heat and add peanut butter, marshmallows, and vanilla extract. Stir until marshmallows and peanut butter are melted and blended. Pour into the prepared pan.

Allow to cool and cut into squares.