Preheat oven to 425°F (220°C). Grease or line a muffin tin.
In a large bowl, whisk flour, baking powder, baking soda, salt, and sugar.
In another bowl, whisk eggs, buttermilk, oil, and vanilla.
Combine wet and dry ingredients. Stir gently until just mixed.
Fold in raspberries and chocolate chips carefully.
Fill muffin cups to the top. Sprinkle with coarse sugar if using.
Bake at 425°F for 5 minutes, then lower to 350°F and bake 15–17 more minutes.
Cool in pan 10 minutes, then transfer to rack.