Preheat your oven to 350°F (175°C). Grease a 9×5-inch loaf pan or line it with parchment.

In a large bowl, whisk together the gluten-free flour, baking powder, baking soda, salt, cinnamon, and nutmeg.

In another bowl, cream the dairy-free butter with brown sugar until light. Add eggs one at a time, then stir in pumpkin puree, almond milk, and vanilla until smooth.

Fold the dry ingredients into the wet mixture until just combined. Avoid over-mixing to keep the cake tender.

In a small bowl, combine oat flour, brown sugar, melted dairy-free butter, cinnamon, and salt until crumbly.

Pour half the batter into the pan, sprinkle half the streusel, add the remaining batter, and finish with the rest of the streusel.

Bake for 45–55 minutes or until a toothpick inserted into the center comes out clean. If the top browns too quickly, tent with foil.

Let cool in the pan for 15 minutes, then transfer to a wire rack. Serve warm or at room temperature.