Line a rectangular loaf or cake tin (I used a 25cm long x 12cm wide rectangular tin - a different shaped tin might produce different thicknesses) with baking paper and put aside.
Add into a food processor oats, cocoa powder, dates, sunflower seeds, vanilla essence and a big pinch of salt. Process for 30 seconds. Add the ¼ cup of coconut oil and process for minute.
Add mixture to the lined loaf tin and evenly press down to form a base - fingertips are best for this. Try and get it as even as possible! Place in the fridge.
Immediately wash out your food processor, then add all ingredients for the peppermint filling into the blender. Blend for a minute and a half - you may need to scrap down the sides of the blender a few times!
Remove loaf tin from the fridge, and tip peppermint filling contents in. Using your finger tips or a spatula, press filling down, once again trying to get it as even as possible. Place in fridge.
Break up the dark chocolate into smaller squares, and melt (microwave or Bain Marie method). If using the microwave be careful not to let it overheat. Once melted, add the 1 Tbsp of olive oil and mix until smooth and glossy. Pour over slice and place back in the fridge to set.
As soon as the chocolate has hardened, using a shark knife slice slab into 9 pieces length ways. Then slices each piece into half - you should get 18 pieces in total. Clean the knife on an old tea towel between cuts to keep the layers tidy. Don’t leave the chocolate to harden for too long before cutting…otherwise it might crack when cut!
Store in the fridge.