- Prepare your pan: Line a 9x13-inch pan with parchment paper or grease it well. Set aside.
- Melt the butter: In a medium saucepan over medium heat, melt the butter.
- Combine sugar and milk: Add the evaporated milk and sugar to the melted butter. Stir until the sugar dissolves and everything is well combined.
- Boil the mixture: Bring the mixture to a boil, stirring continuously. Once boiling, stir for 5 minutes or until the temperature reaches 238°F (soft-ball stage) on a candy thermometer. Consistent stirring is crucial to prevent burning.
- Remove from heat: Take the saucepan off the heat once the mixture reaches 238°F (or after 5 minutes of boiling when not using a thermometer).
- Add marshmallow fluff: Quickly stir in the marshmallow fluff, vanilla extract, and salt. The marshmallow fluff will begin to melt from the heat of the sugar mixture.
- Melt the chocolate: Add the chocolate chips and stir until fully melted and incorporated into the mixture. You might have to stir vigorously at this step until everything is melted and mixed. The fudge should still be somewhat runny at this stage.
- Add the peanut brittle: Stir in the chopped peanut brittle, ensuring it is evenly distributed throughout the fudge.
- Transfer to the pan: Pour the fudge mixture into your prepared baking dish, spreading it out evenly.
- Let the fudge set: Allow the fudge to cool at room temperature for a few hours until fully set.
- Cut and store: Cut the fudge into your desired size and enjoy! Store leftovers in an airtight container at room temperature for up to one week.
Makes approximately 30 servings, depending on the size.