Step 1: Preheat your oven to 375°F (190°C) and line a 12-cup muffin tin with paper liners or grease with non-stick spray.
Step 2: In a medium bowl, whisk together the flour, baking powder, cinnamon, and salt until well combined.
Step 3: In a large bowl, whisk the eggs with the granulated sugar and brown sugar until the mixture is smooth and slightly pale.
Step 4: Stir in the vegetable oil, milk, and vanilla extract until fully incorporated into the egg mixture.
Step 5: Gently fold the dry ingredients into the wet ingredients using a spatula. Stop as soon as no large streaks of flour remain; do not overmix.
Step 6: Toss the diced pears with a pinch of flour, then fold the pears and toasted walnuts into the muffin batter.
Step 7: Scoop the batter evenly into the prepared muffin tin, filling each cup about three-quarters full.
Step 8: Bake for 18-22 minutes, or until a toothpick inserted into the center of a muffin comes out clean.
Step 9: Allow the pear and walnut muffins to cool in the pan for 5 minutes before transferring them to a wire rack to cool completely.