Preheat the oven to 160c/320f.Place the dates and hot water in a large bowl or jug and leave to soak for 3 minutes. Add in the banana, then blend to a puree using a hand blender. Add in the coconut oil and stir until it has melted into the puree.Add in the rest of the ingredients and stir until everything is well mixed. You should have a slightly damp, clumpy mixture.Pour out the ingredients onto a metal baking tray and flatten with the back of a spoon. Squash some of the mixture together so you get some nice clumpy bits.Place in the oven and cook for 35 minutes. After the first 15 minutes, check the granola every 5-6 minutes to make sure it doesn't burn and to let any steam out of the oven. The edges will start to brown quicker, so each time you check the granola, move it around a little, and move any darker bits away from the edges.Take out of the oven and leave to cool completely, then break apart any larger clumps using your fingers. Pour into an airtight container until ready to use.