Whisk flour, baking powder, baking soda and salt in a large bowl. Whisk egg, buttermilk, oil, sugar and vanilla in a medium bowl. Make a well in the center of the dry ingredients, add the wet ingredients and whisk just until combined. Resist overmixing—it will make the pancakes tough.
Let the batter sit, without stirring, for 10 to 15 minutes. As the batter rests, the baking powder forms bubbles that create fluffy pancakes and the gluten in the flour relaxes to make them more tender.
Coat a large nonstick skillet or griddle with cooking spray; heat over medium heat. Without stirring the batter, measure out pancakes using about ¼ cup batter per pancake and pour into the pan (or onto the griddle). Cook until the edges are dry and you see bubbles on the surface, 2 to 4 minutes. Flip and cook until golden brown on the other side, 2 to 4 minutes more. Repeat with the remaining batter, coating the pan with cooking spray and reducing the heat as needed.