Preheat the oven to 350 degrees F. Grease a 9x13 baking dish.
In a large bowl, whisk together 1 cup egg whites, 1-½ cups plain non-fat Greek yogurt, ⅓ cup monk fruit maple syrup, 1 cup skim milk, 1 tsp vanilla extract, 1 tsp cinnamon, and ½ tsp salt until smooth.
Stir in 2 cups rolled oats, ¼ cup chia seeds, and ¼ cup hemp hearts. Let the mixture sit for 10 minutes so the oats and chia start soaking up the liquid. Then pour into the prepared dish and spread evenly.
Make the topping: in a bowl, stir together 2 cups chopped pecans, ½ cup dark brown sugar, 4 tbsp butter, 6 tbsp maple syrup, 2 tsp cinnamon, and ¼ tsp salt until the pecans are fully coated. Scatter evenly over the oats.
Bake for 35-40 minutes, until the center is set and the topping is bubbling and deep golden. If the pecans are browning too fast, tent loosely with foil for the last 10 minutes.
Let cool for 10 minutes before slicing so the sticky topping can firm up. Cut into 8 squares and top each with ¼ cup of the 2 cups plain non-fat Greek yogurt before serving.