Preheat oven to 375°F (190°C).
Line a 12-cup muffin tin with paper liners or grease well.
In a medium bowl, whisk flour, baking soda, baking powder, salt, and spices.
In a large bowl, whisk brown sugar, granulated sugar, and eggs until smooth.
Whisk in pumpkin purée, oil, buttermilk, and vanilla.
Gently fold dry ingredients into wet until just combined.
Fold in chocolate chips.
Divide batter evenly among muffin cups (they will be full).
Sprinkle each with extra chocolate chips and a generous spoonful of the toasted pumpkin seeds.
Bake 20–24 minutes, or until a toothpick inserted in the center comes out clean with a few moist crumbs.
Cool in the pan for 5 minutes, then transfer to a wire rack. Serve warm or at room temp.