Prep the pan. Lightly grease a 9-inch pie dish or springform pan.
If using a springform, line the bottom with parchment for easy removal.
Make the crust. Pulse graham crackers or oat cookies into fine crumbs. Mix with melted coconut oil or butter and a pinch of salt until it resembles damp sand.
Press and chill. Firmly press the mixture into the pan’s base and slightly up the sides. Use the bottom of a glass to pack it tight.
Chill in the fridge while you make the filling.
Whisk the dry. In a large bowl, whisk protein powder with a pinch of salt (and cinnamon, if using). This helps prevent lumps later.
Add the creamy base. Add almond butter, Greek yogurt, vanilla, and maple syrup. Stir slowly at first, then more vigorously until smooth.
Adjust consistency. Add almond milk 1 tablespoon at a time until the filling is thick but spreadable—like a fluffy mousse.
You may not need the full 1/2 cup.
Optional boosters. Fold in ground flaxseed or chia if you want extra fiber and thickness. Taste and adjust sweetness or salt.
Fill the crust. Spoon the mixture into the chilled crust. Smooth the top with an offset spatula or the back of a spoon.
Chill to set. Cover and refrigerate for at least 4 hours, preferably overnight, until firm enough to slice cleanly.
Top and serve. Just before serving, add shaved dark chocolate, sliced almonds, a few raspberries, or a sprinkle of flaky salt.
Slice with a warm, sharp knife for the neatest wedges.