Gently melt the coconut oil over a low heat or in the microwave. Stir in maple syrup and vanilla extract, if wished. Pour into the dry ingredients and mix well. Tip into a large baking or roasting tray, spreading the mix out to form a thin layer. Bake for 10 minutes. Remove from the oven and toss. Return to the oven and bake a further 15-20 minutes, tossing again to ensure even cooking. The granola should be golden brown. Remove from the oven and cool completely on the tray.