Prep: Line a 8″x3″ loaf pan with parchment paper. Make sure there is extra paper hanging over two sides of the pan, to make the bars easier to remove (see blog post photos for reference).
Base Layer: Whisk the almond flour, cacao powder, and a pinch of salt together in a medium bowl. Pour in the maple syrup, then begin mixing with a spatula. Mix until all of the flour has absorbed the maple syrup and the dough sticks together when pinched; you may need to switch to your hands at some point. Transfer the base layer to the lined pan and use a damp spatula or fingertips to evenly press the dough into the base; place in the freezer while you prepare the filling.
Almond Butter Layer: Use a spatula to mix the almond butter, maple syrup, vanilla, and salt together in a separate medium bowl. Add the melted coconut oil once combined and mix until completely incorporated – the filling will begin to stick to the sides of the bowl, but still be runny. Pour this mixture into the lined pan over the base layer, using a spatula to smooth out the top. Return the pan to the freezer.
Chocolate Layer: Add the dark chocolate and coconut oil (if using) to a microwave-safe bowl and microwave for 60 seconds; remove from the oven and use a clean and dry spatula to stir the chocolate and oil together until all pieces of chocolate have completely melted. Pour the melted chocolate mixture over the almond butter mixture. You can use a spatula to spread it around but it should still be quite runny, so you can also gently shake the pan back and forth to help it spread evenly. Sprinkle Maldon salt over the melted chocolate, then place in the freezer for at least 30 minutes, or until the bars have hardened.
Slice: Run a sharp knife along the un-lined edges of the pan, then grab the two “flaps” of parchment paper to remove the bars and transfer to a cutting board. Use a sharp, clean knife to slice the bars into 12-18 even pieces, or as desired. I like to run the knife under hot water and wipe it off between cuts for cleaner cuts. To prevent the chocolate layer from cracking I have found it easiest to use a knife to “score” the top chocolate layer first; once you have made shallow grooves in the chocolate it is easier to cut all the way through the bar.
Serve: As desired; these bars will soften over time at room temperature and are best served slightly chilled. Store leftovers in an airtight container in the fridge for up to 10 days for a fudgy texture, or in the freezer for up to 2 months for a firmer bar.