Preheat your oven to 350°F (175°C) and grease your loaf pan. Line with parchment paper if desired.
Mix dry ingredients. In a medium bowl, whisk together flour, baking soda, baking powder, salt, and pumpkin pie spice.
Combine wet ingredients. In a large bowl, whisk together pumpkin puree, sugars, eggs, oil, milk, and vanilla until smooth.
Add dry to wet. Gently fold the dry mixture into the wet mixture using a spatula until just combined. Do not overmix.
Pour and bake. Pour batter into the prepared loaf pan. Bake for 55–65 minutes, or until a toothpick inserted in the center comes out clean.