Preheat oven to 400ºF(204ºC). Spray 18 wells of two 12-count muffin pans with non-stick spray or line the wells with cupcake liners. Set aside.
In a large bowl, toss together the flour, baking powder, and salt. Set aside.
3 cups (360g) all purpose flour, 4 teaspoons baking powder, ½ teaspoon salt
In a medium size bowl, whisk together the butter, granulated sugar, and brown sugar until smooth. Add the eggs, buttermilk, and vanilla extract and whisk again until everything is combined.
½ cup (114g) unsalted butter, ½ cup (100g) granulated sugar, ½ cup (100g) brown sugar, 2 large eggs, 1 cup buttermilk, 1 and ½ teaspoons vanilla extract
Pour the wet ingredients into the dry ingredients and stir gently with a spatula until just combined. Carefully fold the berries (reserving some for tops of the muffins-- about 1/4 cup) into the muffin batter, being aware the color may spread a bit.
2 cups mixed fresh berries3
Spoon batter equally into prepared muffin pans. Place additional berry pieces in the tops of the muffins if desired. Bake muffins for 5 minutes, then reduce heat to 350ºF(177ºC) and bake for an additional 16-18 minutes until tops start to brown and a toothpick inserted in the center comes out mostly clean. Remove from oven and allow to cool completely on a wire rack. Muffins will stay fresh in an airtight container at room temperature up to 3 days or in the refrigerator up to one week. Muffins freeze well, up to 2 months. Thaw in microwave for 45-60 seconds before eating.
Notes
It is always a good rule of thumb to use room temperature eggs when using room temperature butter. To bring eggs to room temperature quickly, place in a bowl of warm water for 10 minutes.
If you don't have buttermilk, you can easily make your own: see my post about homemade buttermilk.
You may also use fresh blueberries or a combination of fresh and frozen. I used whole blueberries, whole and halved raspberries, and chopped strawberries. Any combination of berries is fine, totaling 2 cups.
Nutrition Disclosure
All nutritional values are approximate and provided to the reader as a courtesy. Changing ingredients and/or quantities will alter the estimated nutritional calculations.