In a large bowl, combine the butter, peanut butter, crumbs, and sugar. Mix well until well combined.
Pour mixture into a 9x13 pan and spread out to cover the bottom of the pan. Place into the fridge to firm up. (about 1 - 1/2 hours)
Once batter is firm, take out of the fridge and using a teaspoon, scoop out enough to roll into a walnut size ball. Place the rolled truffles onto a wax paper covered cookie sheet.
Once you have rolled all of the peanut butter balls, place them in the freezer to firm up as the peanut butter will soften the longer it is out of the fridge. (about 30 minutes or so should be sufficient)
Melt the dark chocolate in a double boiler to avoid burning. The warm water will keep the chocolate from hardening while dipping the truffles.
Dip each truffle in the dark chocolate and shake off the excess chocolate. Place the truffles back onto the wax paper once dipped.
Place the chocolate covered truffles into the fridge to harden, or if you want them solid faster, into the freezer for a 1/2 hour or so.
Store the completed truffles in an airtight container in your fridge.