Preheat oven to 400 degrees F (200 degrees C). Lightly spray 12 muffin cups with cooking spray.
Mix flour, oats, brown sugar, baking powder, 1/4 teaspoon ground ginger, and salt together in a bowl; form a well in the center of flour mixture. Whisk milk, oil, and egg together in a small bowl and pour into well. Stir until batter is just moistened; fold in pear and walnuts. Fill prepared muffin cups with batter.
Mix oat bran and remaining 1/2 teaspoon ground ginger together in a small bowl; sprinkle over batter.
Bake in the preheated oven until a toothpick inserted in the center of a muffin comes out clean and tops are brown, 18 to 20 minutes. Cool in the pan for 5 minutes before removing from muffin cups. Serve warm.