Preheat your oven to 375°F (190°C).
In a medium bowl, whisk together the flour, baking powder, baking soda, salt, and spices.
In a large bowl, cream together the softened butter and brown sugar until light and fluffy, about 2–3 minutes.
Beat in the eggs one at a time, mixing well after each addition. Stir in the vanilla extract.
Gradually add the dry ingredients to the wet mixture while alternating with the milk. Mix until just combined.
Gently fold in the diced pears using a spatula.
Divide the batter evenly among your prepared muffin cups, filling each about two-thirds full.
Bake for 20–25 minutes or until a toothpick inserted into the center comes out clean.
Allow muffins to cool in the pan for about five minutes before transferring them to a wire rack to cool completely.