Place rack in the upper third of the oven and preheat oven to 350 degrees F.
Grease an 8×8-inch square pan. Line with parchment paper and grease the parchment paper. Set aside.
In a large bowl, whisk together flour, baking powder, baking soda, salt, and spices. Stir in the sugars until well combined. Set aside.
In a medium bowl, whisk together melted butter, eggs, buttermilk, and vanilla extract.
Add the wet ingredients to the dry ingredients and gently stir to incorporate. Once the dry ingredients are almost fully incorporated, fold in the pears.
Spoon the batter into the prepared pan.
To make the crumble, in a small bowl combine flour, sugar, cinnamon, salt, and butter. Use your fingers to break the butter down into the dry ingredients until crumbly. Generously sprinkle topping on top of cake batter.
Bake for 25 to 35 minutes or until a skewer inserted in the cake comes out clean.
Remove from the oven and allow to cool for at least 30 minutes before serving. Cake will last for 3 days, wrapped well and stored in the refrigerator.
