Preheat your oven to 375°F (190°C) and lightly grease a small individual-sized baking dish.
In a small saucepan over medium heat, combine the frozen cherries, lemon juice, cinnamon, and arrowroot powder.
Stir the cherry mixture constantly for 3-5 minutes until the juices thicken into a glossy sauce, then pour into the prepared baking dish.
In a separate mixing bowl, combine the rolled oats, vanilla protein powder, and sea salt.
Add the egg white and water to the dry ingredients, stirring until a stiff dough forms.
Place the dough between two pieces of parchment paper and roll it out to a 1/4-inch thickness, then cut into thin strips.
Carefully weave the dough strips over the cherry filling in a lattice pattern, trimming any excess from the edges.
Bake for 15-18 minutes or until the oat lattice is firm and lightly browned.
Let the pie cool for 5 minutes to allow the filling to set.
Serve warm with a generous dollop of Greek yogurt on top for a creamy finish.