Preheat oven to 350°F and lightly spray an 8×8-inch baking dish.
Mix the swirl ingredients in a small bowl and set aside.
In a large bowl, whisk together the oat flour, protein powder, baking powder, salt and pumpkin pie spice.
In a separate bowl, whisk the egg whites, pumpkin purée, applesauce, Greek yogurt, vanilla and almond milk, reserving the final 2 tablespoons of milk.
Add the wet ingredients to the dry and stir until combined. The batter should be thick but spreadable. Add the reserved milk only if needed.
Spread half the batter into the baking dish and sprinkle with half the cinnamon-spice mixture. Add the remaining batter, finish with the remaining spice mixture and run a knife through it to create a swirl.
Bake for 28–33 minutes, until the centre is set and a toothpick comes out mostly clean. Let cool for 10–15 minutes before cutting.
