Heat the oven and prep the pan. Set the oven to 350°F and grease a 9×5-inch loaf pan, or line it with a parchment sling.
Whisk the dry ingredients. In a large bowl, whisk together the flour, baking soda, baking powder, cinnamon, cardamom, nutmeg, and salt.
Whisk the wet ingredients. In a second bowl, whisk the melted butter with the brown sugar and granulated sugar until smooth, then whisk in the eggs and vanilla.
Combine, then fold in the pears. Pour the wet mixture into the dry and stir just until no dry flour remains. Fold in the diced pears — a few streaks of flour are fine; overmixing makes a tough loaf.
Make the crumble. In a small bowl, stir together the flour, brown sugar, and cinnamon. Cut in the cold butter with a fork until the mixture looks like coarse crumbs. Pop it in the fridge while you finish the batter so the butter stays cold.
Pan and top. Scrape the batter into the prepared pan and smooth the top. Sprinkle the crumble evenly over the batter and press it lightly so it sticks.
Bake 55 to 60 minutes. Bake until a toothpick inserted in the center comes out clean or with a few moist crumbs, and the top is golden. Start checking at 50 minutes — juicy pears can stretch the bake.
Cool before slicing. Let the loaf rest in the pan for 10 minutes, then lift it out onto a wire rack and cool completely before slicing, so the crumb sets.
