Line an 8x8 inch pan with parchment paper or foil, leaving an overhang on the sides.
In a large saucepan, combine the granulated sugar, butter, and evaporated milk. Cook over medium heat, stirring constantly, until the butter is melted and the mixture is smooth. Bring to a boil and cook for 5 minutes, stirring occasionally.
Remove the saucepan from the heat. Stir in the white chocolate chips until melted and smooth. Then, stir in the strawberry frosting and vanilla extract until well combined.
Pour the mixture into the prepared pan and spread evenly. If desired, swirl in extra strawberry frosting for a marbled effect.
Let the fudge cool completely at room temperature for about 2-3 hours, or until firm.
Once firm, lift the fudge out of the pan using the overhang and cut into squares.
Notes
Store fudge in an airtight container at room temperature for up to 1 week.