Combine the graham cracker crumbs and butter in a medium bowl. Stir until the cookie crumbs are well coated.
Press the crumbs tightly into the bottom and up the sides of a 9-inch pie plate. Freeze while you make the filling.
Make the filling
Sprinkle the gelatin over the 2 tablespoons of cold water in a small microwave-safe bowl and set aside.
In a medium bowl, combine the heavy cream and confectioners sugar. Beat on medium-low speed until whipped and fluffy; about 5 minutes.
Add the thawed raspberries to the bowl of a food processor and process until smooth. Run the puree through a fine-mesh sieve and discard the seeds.
Add ¼ cup of the raspberry puree to the gelatin. Heat in the microwave for 1 minute. Stir until the gelatin is fully dissolved. Pour back into the bowl with the remaining puree and stir to combine.
Pour the raspberry mixture into the bowl with the whipped cream mixture. Use a silicone spatula to carefully fold everything together until well combined.
Pour the raspberry mousse over the prepared crust. Use an offset spatula to smooth the top.
Cover with plastic wrap and refrigerate for at least 6 hours or overnight.
How to serve
Just before serving, pipe swirls of whipped cream over the top if desired and garnish with fresh strawberries.
Run a sharp knife under hot water to warm the blade. Very carefully dry the blade and slice the pie. Repeat with each slice.
Notes
The no-bake graham cracker crust can be crumbly, making it difficult to get neat pie slices. You may wish to bake the crust instead. If so, stir 2 tablespoons of sugar into the graham cracker mixer. Press it into the pie dish and bake for 10 minutes at 350°F. Cool to room temperature then refrigerate while you make the filling.
Make ahead tip
Keep the pie covered with plastic wrap and store in the refrigerator for up to 5 days.
Or wrap the pie tightly in a layer of plastic wrap. The wrap tightly with two layers of aluminum foil. Freeze for up to 2 months. Thaw overnight in the refrigerator.