Combine semi-sweet chocolate and peanut butter. Microwave on high 1.5 to 2 minutes, until mixture is melted and smooth.
While the chocolate and peanut butter are melting, cover a half cookie sheet with parchment paper. Open your sleeve of crackers and lay them out as evenly as possible- I like to overlap some of mine to add some height difference.
Put white chocolate chips in a separate bowl and microwave on high 1 minute. Stir to complete melting.
While the white chocolate is melting, pour chocolate- peanut butter mixture over crackers. Use a rubber spatula to spread chocolate around, covering all the crackers. This isn't an exact science- don't worry about spreading it pretty!
Once the white chocolate is melted, pour it over the chocolate crackers. I like to use lines, it helps to make the marbling effect look better.
Using a toothpick, run lines through the white chocolate, back and forth over the crackers. Feel free to get a little crazy here- it's pretty hard to mess up!
Let sit in a cool place to solidify. I like to stick the pan in the fridge or freezer, because I'm impatient!
Cut into pieces with a sharp knife. Serve and Enjoy!