16 ounces milk chocolate chips or couverture disks
10 ounces (1 2/3 cups) peanut butter chips
1 cup mini pretzels
2/3 cup banana chips, broken into large pieces
2/3 cup coarsely chopped roasted peanuts
Line a standard (18x13-inch) baking sheet with wax or parchment paper, and set it aside.
In a microwave-safe bowl, melt the peanut butter chips in 20-second bursts in the microwave, stirring after each heating. (Alternatively, melt in a double-boiler.) Drape a quart-sized plastic bag over a cup or mug, then use a spatula to transfer the melted peanut butter chips into the bag.
In another microwave-safe bowl, melt the milk chocolate in 20-second bursts in the microwave (or over a double boiler), stirring after each heating, until just melted and liquidy. (See Recipe Notes for tempering instructions, if you'd like to do that!)
Pour the milk chocolate onto the lined baking sheet, and using a spatula, spread it into an even layer about 1/4-inch thick.
Snip off a corner of the bag with the melted peanut butter chips, then pipe it out onto the milk chocolate in 1/2-inch thick stripes, covering the surface of the chocolate.
Drag your spatula through the peanut butter and chocolate, and then again going the opposite direction, creating a swirled pattern. Repeat down the length of the chocolate.
While the chocolate is still soft and liquidy, quickly press the pretzels into the surface of the chocolate, spacing them about 1-inch apart. Sprinkle the banana chips and chopped peanuts over top, and press gently into the chocolate with the palm of your hand.
Place the sheet of bark in the fridge and allow it to set up for an hour, until completely solid. Cut or break it into large 2- to 3-inch pieces. Serve or store in an airtight container for up to 1 month.