Line an 8x8 inch square baking dish with parchment paper. In the bowl of a food processor, combine the peanut butter, dates, and vanilla. Pulse until well combined and the dough clumps together easily.

Press the mixture into the prepared baking dish. Sprinkle the rice krispies over top, gently pressing them into the peanut mix to adhere.

Transfer to the freezer and freeze until firm, 30 minutes to 1 hour.

Melt the chocolate in the microwave on 30 second intervals, stirring after each interval until melted and smooth. Let cool 10 minutes.

Cut into 16 bars, shaking off any excess rice krispies that are not sticking. Cover in chocolate and top as desired, with peanuts or more rice krispies.

It's easiest if the bars are very cold when doing this step. Let the chocolate set up, about 10 minutes. Keep stored in the fridge.