Get an 8x8 inch square pan ready by lining it with parchment paper. Make sure some paper hangs over the edges – this will be your secret weapon for easy lifting later!
In a microwave-safe bowl, combine your semi-sweet chocolate chips with about half of the sweetened condensed milk (around 2/3 cup). Pop it in the microwave for 30 seconds, then stir well. Repeat this in 30-second bursts, stirring each time, until you have a beautifully smooth, melted chocolate mixture.
Grab another microwave-safe bowl. Add the creamy peanut butter and the rest of the sweetened condensed milk. Microwave in 30-second intervals, stirring vigorously after each, until it's wonderfully smooth and creamy.
Pour the melted chocolate mixture into your prepared pan and spread it evenly to form the first layer. Gently spoon the peanut butter mixture on top of the chocolate layer, spreading it out. For a pretty swirl effect, take a sharp knife (lightly sprayed with non-stick spray for ease) and gently drag it through both layers. If you prefer distinct layers, just skip the swirl!
Place your pan in the refrigerator and let it chill for at least 4 hours, or until it's completely firm. This is crucial for that perfect fudge texture!
Once firm, lift the fudge out of the pan using the parchment paper overhang. Cut it into 16 delightful bite-sized squares. Get ready to enjoy this easy, no-bake summer treat!