Rinse the raspberries and set them aside to drain.
Break graham cracker sheets into small pieces, filling 2 1/2 cups. How many sheets you need depends on the size of the graham crackers. (See the recipe notes.)
Use a food processor to mix the graham cracker pieces, melted butter, brown sugar and peanut butter. Pulse several times until the graham cracker pieces are finely crumbed and everything is mixed together.
Press the crust firmly and evenly onto the bottom and sides of a pie pan. (See the recipe notes.) The crust may not reach all the way up the sides, but that's okay. Put the crust in the refrigerator to chill.
Prepare the filling while the crust is chilling. Mix the water, sugar, cornstarch and butter in a medium sauce pan over medium heat, stirring constantly. Allow the butter to melt and the sugar to dissolve before bringing the mixture to a boil. Keep it at a boil for 2 minutes (still stirring constantly) before removing the pan from the heat. The mixture should be thick and cloudy. Stir in the gelatin and then let it rest for 15 minutes.
Take the crust out of the fridge. Spread the raspberries in the crust and then pour the gelatin mixture evenly on top. Let the pie chill in the refrigerator for at least 30 minutes before serving. Top with a dollop of whipped cream and enjoy!