Line a 9" x 13" baking sheet with foil. place graham crackers in a single layer over the foil. You may need to break the graham crackers to fill in the smaller spaces. Fill up the pan as best you can.
In a medium saucepan over medium heat, melt the butter. Add the brown sugar and cook until sugar has dissolved and it just begins bubbling.
Pour the sugar mixture evenly over graham crackers. Use the back of a spoon to spread the sugar mixture so it's evenly distributed.
Immediately sprinkle peanut butter chips over the top of the sugar mixture..
Preheat oven to 350 degrees F. Place the baking sheet in oven while it preheats. Check on the candy every 3 to 5 minutes until peanut butter chips look a little melted. Carefully remove baking sheet from oven.
Use an offset spatula or back the of a spoon to spread the melted peanut butter chips evenly over the graham crackers. {The peanut butter chips don't melt on their own the same way chocolate chips do. They need the extra heat boost.} Sprinkle the candy with pecan pieces. Let the candy cool until you are able to handle it with your bare hands. Transfer the candy to fridge and chill for at least 1 hour to overnight.
Break candy into pieces. Try not to eat it all yourself. ;)