Will this make an energy bar???

I'd leave the butter out – it melts much sooner than chocolate. I haven't done what you describe, but I make a cake glaze of butter and chocolate and it stays pretty soft at room temp.

You might want to go with a hard dark chocolate. As Deborah said the butter will melt too fast, so leave that out. What *I* would do to make up for the loss of calories from the butter is mix in some unflavored or chocolate "weight gain powder" into the fruit and nut mix. I would also mix in some oats, organic cracked wheat, or other complex carbs.

as others have said nix the butter and use a darker chocolate

now here are a few hints…

wrap them in waxed paper and then put them in a zipper bag… if they do melt and reset the waxed paper will make it easy for you

another hint – store them deeper in your pack – this will insulate them somewhat

There are alot of energy bars on the market and alot of the more calorie ones are generally a "protein" bar. I take energy gu's and put it on top of the bar. A little messy, but you can add some moisture to the bar and add different taste combinations as well as increasing the carbohydrate content in the bar.