In a large bowl using an electric hand mixer or using a stand mixer fitted with the whisk attachment, whisk 2 cups heavy cream and 2 tbsp sugar to stiff peaks. Set aside. If not using immediately, chill in the fridge.
Place a layer of graham crackers at the bottom of a deep 8×8 inch baking dish.
Evenly spread a heaping cup of cream mixture on top of your graham crackers.
Assemble a layer of peach slices on top of that.
Repeat by covering the peaches with graham cracker cookies. Be sure to cover the entire layer; cut the cookies to fit. Then cover with another layer of cream and top with more peaches.
Chill the peach icebox cake in the fridge overnight or freeze for at least 4 hours (see notes).
The graham crackers I use are squares (see post for complete step-by-step photos). I used a total of 21 cookies to fill my 8×8 inch baking dish.
If using fresh peaches, toss the peach wedges in cinnamon before assembling your cake.
Freezing will result to a more ice cream cake-like end product which you would have to thaw several minutes before serving. Chilling will result to a creamy, ready-to-eat cake out of the fridge.