Preheat your oven to 350°F (175°C). This ensures the bread starts baking at the correct temperature for even rise and a golden crust.
In a large mixing bowl, whisk together the pumpkin purée, brown sugar, and melted butter for about 2–3 minutes, or until the mixture looks smooth and glossy with no visible streaks of butter.
Add in the eggs, one at a time, whisking well after each addition until the batter is thick, creamy, and slightly lighter in color.
Then whisk in the milk and vanilla extract until just combined. Set aside the pumpkin mixture while you mix the dry ingredients.
In a medium bowl, whisk together the gluten-free flour, baking powder, baking soda, cinnamon, ginger, nutmeg, cloves, and salt until everything is evenly distributed. This ensures even flavor and rise throughout the loaf.
Pour the dry mixture into the wet mixture, then use a spatula or wooden spoon to gently fold until no streaks of flour remain. Be careful not to overmix — overmixing can make the bread dense. The batter should be thick and smooth.
Line a 9x5-inch loaf pan with parchment paper, leaving some overhang on the sides for easy lifting once baked. Lightly grease the exposed sides of the pan with butter or oil if needed.
Pour the pumpkin batter evenly into the prepared pan, then sprinkle the chilled crumble evenly over the top. Gently press it down just a bit so it adheres to the batter but still stays textured on top.
Bake in the preheated oven for 45–55 minutes, or until the top is golden brown and a toothpick or cake tester inserted into the center comes out clean or with just a few moist crumbs (no wet batter). If the crumble starts browning too quickly near the end, you can tent the loaf loosely with foil.
Let the bread cool in the pan for 10–15 minutes, then use the parchment paper to lift it out onto a wire rack. Allow it to cool completely before slicing — this helps the texture set and prevents it from crumbling apart.