Preheat your oven to 175°C (350°F). Lightly grease the base and sides of a square 8" pan with some oil or vegan butter, then line with parchment paper.
In your food processor, combine the flour, milled flaxseed, coconut sugar, sea salt, peanut butter, vegan butter, and water until the ingredients stick together to form a dough. Evenly press the dough into the base of the pan and smooth it out with a spatula or flat bottomed glass. With a fork, gently prick the dough several times.
Bake for 15-18 minutes until slightly browned, then allow to cool to room temperature.
To prepare the caramel, add all of the ingredients to a heat-resistant bowl. Heat over a double boiler (bain-marie) while stirring until all of the ingredients have melted into a smooth caramel.
Pour the caramel on top of the shortbread layer and place in the freezer to set for a minimum of 4 hours (overnight works well).
Melt the chocolate and peanut butter over a double boiler (bain-marie) and stir to combine. Pour the chocolate over the caramel layer and place it in the fridge to set for 15-20 minutes.
To slice, place a sharp knife in a jug of boiling water to heat it. Wipe the knife dry and gently cut, allowing the heat from the knife to melt through the slices.
Store these slices in an airtight container in the fridge and consume within 3-5 days. Alternatively, you can freeze any unused portions and defrost them as needed.
Peanut butter: Feel free to swap it out for another nut butter of your choice, or a mix if you're trying to clear out the cupboards!
White chocolate: a swirl of dairy-free white chocolate would be heavenly on top of these bars. Add it when you add the topping (before it melts) and use a knife to create a swirl effect
Roasted salted peanuts: just before your chocolate topping sets, add a handful of crushed peanuts on top of the tray bake, for those snickers vibes!
Miso: miso and caramel are a match made in heaven, take that umami flavor to the next level by adding a teaspoon of your favorite miso paste to the caramel ingredients.