Preheat your oven to 375°F (190°C). Grease a muffin tin or line it with paper liners.
Mix Dry Ingredients:
In a bowl, whisk together flour, baking powder, and salt.
Cream Butter and Sugar:
In another large bowl, beat the butter and sugar until light and fluffy. Add eggs one at a time, beating after each addition. Stir in vanilla extract.
Combine with Dry Ingredients:
Alternately add the dry ingredients and buttermilk to the butter mixture, starting and ending with the dry ingredients. Fold gently until just combined.
Add Raspberries:
Gently fold in the raspberries, being careful not to overmix to avoid crushing the berries.
Bake the Muffins:
Scoop the batter into the prepared muffin tin, filling each cup about 3/4 full.
Bake for 20-25 minutes, or until a toothpick inserted into the center comes out clean.
Notes
Let the muffins cool in the pan for a few minutes, then transfer to a wire rack to cool completely.