In a large bowl, whisk together the all-purpose flour, baking powder, baking soda, kosher salt, light brown sugar, ground cinnamon, ground ginger, and ground nutmeg until evenly combined.
In a separate bowl, whisk the milk, pumpkin puree, beaten egg, melted unsalted butter, and vanilla extract until smooth.
Pour the wet mixture into the dry ingredients and whisk just until no dry pockets remain; the batter will be thick. If it seems overly stiff, whisk in 1–2 tbsp more milk. Let the batter rest 5 minutes.
Heat a nonstick skillet or griddle over medium heat (about 350°F). Lightly brush the surface with a little vegetable oil.
Scoop 1/4-cup portions of batter onto the hot surface, spacing them apart. Cook until edges look set and bubbles form and begin to pop on top, 2–3 minutes; adjust heat to maintain a gentle sizzle without smoking.
Flip and cook until the undersides are deep golden and centers spring back to a light touch, 1.5–2.5 minutes. Repeat with remaining batter, lightly oiling the pan between batches.