Start by placing both jars of peanuts into the bottom of a 5 to 6 quart slow cooker. Pour the semi-sweet chocolate chips over the peanuts, followed by the milk chocolate chips. Finally, place the chunks of white almond bark on the very top. Do not stir the ingredients yet, as layering helps the chocolate melt evenly without burning.
Cover the slow cooker with the lid and set it to the low heat setting. Let the mixture cook for about 1 hour and 30 minutes. It is important not to open the lid during this time to keep the heat trapped inside. If your slow cooker runs particularly hot, you can check it at the 1 hour mark to ensure nothing is scorching at the bottom.
Remove the lid and stir in the alcohol-free vanilla extract. Use a sturdy spoon to mix all the melted chocolates and peanuts together until the mixture is completely smooth and the peanuts are thoroughly coated. If some of the almond bark is still slightly solid, put the lid back on for another 15 to 20 minutes and then stir again.
Line your countertop or large baking sheets with parchment paper or wax paper. Use a cookie scoop or two spoons to drop rounded tablespoons of the mixture onto the paper. Work quickly before the chocolate begins to firm up in the pot. Let the candy sit undisturbed for at least 2 hours, or until it is completely firm and set to the touch.
