Preheat your oven to 180°C/Gas mark 4.
In a bowl, stir your oats, cacao powder, ground almonds and salt together.
In another bowl, mix together the coconut oil, coconut sugar and maple syrup, then pour this into the dry ingredients and stir well. Finally, stir in the cranberries.
Transfer the mixture to a lined 20cm (8in) square baking tin or mould. Bake for 20 minutes and leave to cool.
Melt the chocolate, if using, on a low heat in a bowl over a saucepan half-full of water, making sure the bowl is not touching the water, then drizzle it on top.
Place the tray in the fridge to allow the chocolate to set, then cut into slices and store in an airtight container for up to a week or freeze for up to 2 months.