Place the oats in a bowl with the flaxseed, salt and cinnamon and stir to combine. Pour over the honey / butter mixture and stir until the oats are thoroughly coated. Add in your mix-ins, then press into the prepared pan (if using chocolate chips, let the mixture cool for a few minutes before adding them so they don’t melt). Bake for 18-20 minutes, then cool completely before cutting into bars. Wrapped well, the bars will last 2-3 weeks.