Prep the pan: Heat the oven to 350°F (175°C). Line an 8x8-inch baking pan with parchment paper, leaving overhang on two sides for easy lifting. Lightly grease the parchment.

Crush the rice cakes: Break rice cakes into a large bowl and crush with your hands until you have small, uneven pieces. Aim for a mix of crumbs and pea-sized bits for better texture.

Make the base: In a small saucepan over low heat, melt the butter and peanut butter with the brown sugar and salt, stirring until smooth. Remove from heat and stir in the vanilla.

Bind the crumbs: Pour the warm peanut butter mixture over the crushed rice cakes. Stir gently to coat evenly. Press this mixture firmly into the prepared pan to form the base.

Add the chocolate layer: Sprinkle the chocolate chips evenly over the base. Follow with the peanut butter chips (or chopped peanut butter cups), chopped peanuts, and shredded coconut if using.

Finish with condensed milk: Slowly drizzle the sweetened condensed milk over the top, covering as much surface as possible. It will seep into the gaps and bind everything together.

Bake: Place in the oven and bake for 18–22 minutes, until the edges are golden and the center looks set and glossy.

Cool and set: Remove from the oven and cool in the pan for at least 1 hour. For clean cuts, chill in the fridge for another 30–45 minutes.

Finish and slice: Sprinkle with flaky sea salt if you like, then lift the slab out using the parchment and cut into 12–16 bars with a sharp knife.