Preheat oven to 350 degrees F (175 degrees C). Line a 9x13-inch baking dish with parchment paper.
Mix oats, milk powder, brown sugar, baking soda, cinnamon, salt, and baking powder together in a bowl. Whisk milk, eggs, oil, and vanilla extract together in a separate bowl; stir into oats mixture just until mixed. Fold cranberries into oats mixture; spoon into prepared baking dish.
Bake in the preheated oven until oatmeal is set, about 40 minutes.
