For extra smooth granola bars, put the peanut butter and honey into a pot and heat it on low until it melts together. I've made these without heating anything and they're just as delicious. I think if you're using a stand mixer, you don't need to heat these up. If you're stirring by hand, it might be easier to use heated ingredients.
Chop the nuts, if you're using them.
Pour peanut butter, honey, oats, your healthy chaser, protein powder, and your extras into a bowl and mix them well.
Grab a 9x9 pan and line it with some parchment paper.
Pour the mixture onto the parchment paper.
Cover it up with another piece of parchment paper, and begin rolling the bars flat. You could also use a can of soda if you don't have a rolling pin that will fit inside the pan.
After your granola mixture is nice and flat, throw the top piece of parchment away and use the bottom one to lift out your granola onto a cooling rack.
Push the granola into a nice firm square on all sides, then let it sit and harden for at least an hour.
Cut your granola bars. I use a pizza cutter.
Notes
This recipe is really flexible. Don't stress about perfect measurements. If you're using chocolate chips and you decide to heat the peanut butter and honey for easier mixing, you should let it cool down so the chocolate doesn't melt. But if you have picky kids and you need to trick them into thinking that they are eating chocolate granola bars you could let it melt and change the color of the whole granola bar. Not that I have ever tricked my kids into thinking they are eating lots of chocolate when they in fact are not.