Line your baking pan with parchment paper and set aside.
Place the peanut butter and butter into a microwave-safe bowl and heat in short bursts, stirring after each, until the mixture is smooth, glossy, and fully melted—about 1-2 minutes.
Pour in the honey or maple syrup and stir well until the mixture is uniform and shiny.
Add the quick oats to the mixture, folding them in until evenly coated, if using.
Stir in the chopped chocolate until most pieces are melted and the mixture turns a rich, chocolatey color—keep stirring until smooth.
Pour the thick, sticky mixture into your prepared pan and use a spatula to press it down evenly, making sure to pack it tightly and smooth the surface.
Place the pan in the fridge for at least 2 hours, or until the mixture is firm and set.
Once set, lift the slab out of the pan using the parchment edges and transfer to a cutting board. Use a sharp knife to cut into 12 even bars or squares.
If desired, melt a few more chocolate pieces and drizzle over the bars for a shiny finish. Let the drizzle set for about 10 minutes.
Enjoy immediately or store in an airtight container in the fridge for up to a week for best freshness.
