Line an 8-inch by 8-inch pan with foil and spray lightly with nonstick spray. This will make it easy to remove the fudge once it has set.
In two separate heat-safe medium bowls, place the peanut butter chips in one and the bittersweet chocolate chips in the other. This separation helps us work with the mixtures easily later on.
In a 3-quart saucepan, combine the granulated white sugar, marshmallow creme, evaporated whole milk, and butter. Cook over medium heat, stirring constantly. You want to keep an eye on this mixture as it heats up.
Keep stirring until the mixture comes to a boil. Once it does, continue stirring for 5 minutes. This step is crucial as it helps the fudge to achieve the right consistency. If you have a candy thermometer, your fudge is ready when it reaches 235°F.
If you don’t have a thermometer, you can do the soft ball test. Take a spoon and drizzle a little fudge into a cup of ice water. If it forms a soft, pliable ball, you’re good to go!
Remove the pan from heat and quickly stir in the vanilla extract. This adds a lovely aroma and flavor to your fudge.
Now, divide the hot mixture: quickly stir one half into the bowl with the peanut butter chips until fully melted. Then do the same with the other half and the bittersweet chocolate chips. Stir them until completely combined.
Once the mixtures are melted, scrape the peanut butter mixture into the prepared pan, smoothing it evenly along the bottom. This will be the first layer of your fudge.
Next, carefully spread the chocolate chip mixture evenly over the top of the peanut butter layer. Take your time to ensure it’s evenly distributed.
Let the fudge sit at room temperature until completely cool. If you’re in a hurry, you can refrigerate it to speed up the process. Once set, cut into small squares and enjoy your delicious homemade fudge!
