Step 1

Line an 8-inch square baking pan with aluminum foil. Coat the foil with cooking spray.

Step 2

In a medium saucepan over low heat, combine the chocolate chips and sweetened condensed milk. Cook, stirring, until melted and smooth, 6 to 8 minutes. Pour the mixture into the prepared baking pan and spread to even out the surface. Top with spoonfuls of the peanut butter. Using a skewer or butter knife, swirl the peanut butter into the chocolate mixture. Sprinkle over the crushed chips and pretzels. Let the fudge cool for 30 minutes on the counter, then lightly cover and refrigerate for 1 hour.

Step 3

Lift the foil out of the pan and peel it from the fudge. Cut into small squares to serve.