Line your square pan with parchment paper, leaving some overhang for easy lifting.
In a microwave-safe bowl, melt the peanut butter and butter together in 30-second bursts, stirring each time until the mixture is smooth and fragrant, about 1-2 minutes.
Add the honey or maple syrup to the melted mixture and stir well until fully incorporated, creating a glossy, cohesive blend.
Pour in the graham cracker crumbs and oats, then fold everything together until the mixture is crumbly but sticks together when pressed.
Using your hands or a spatula, press the mixture firmly into the prepared pan, smoothing the top for an even surface.
Place the pan in the fridge and chill for at least 2 hours, or until the layer is firm and set.
Meanwhile, melt the chocolate chips with coconut oil in a microwave-safe bowl in short bursts, stirring until smooth and shiny, about 30 seconds each time.
Pour the melted chocolate over the chilled peanut butter layer, spreading evenly with a spatula for a glossy finish.
Refrigerate again for about 30 minutes, until the chocolate is set and shiny.
Use the parchment overhang to lift the bars out of the pan, then cut into squares with a sharp knife or cookie cutter.
Serve immediately or store in an airtight container in the fridge for up to a week. Enjoy these rich, chewy, chocolate-topped peanut butter bars!