Preheat oven to 375 F (190 C). Grease and flour a 12-cup regular muffin or 6-cup jumbo muffin pan. Alternatively, you can use baking liners. Set pan aside.
Using a mesh strainer over a large bowl, sift together the flour, baking powder, baking soda, sugar, and salt. Set aside.
2 cups all-purpose flour, 1½ teaspoon baking powder, ½ teaspoon baking soda, ¼ teaspoon salt, ⅔ cup granulated sugar
Add butter, buttermilk, egg, and, vanilla to a blender and blend on low for about 30 seconds. Alternatively, you can add these ingredients to a medium bowl and whisk or mix with a hand mixer on medium for about 30 seconds to a minute.
6 tablespoons unsalted butter, 1 cup buttermilk, 1 large egg, 1 teaspoon vanilla extract
Pour the wet ingredients into the dry ingredients and stir until just combined. Do not overmix. The batter will be thick.
Fold in the white chocolate chips.
½ cup white chocolate chips
Gently fold in the raspberries.
1½ cup raspberries
Spoon the batter into the prepared muffin pan, dividing evenly.
Bake as follows:For regular muffins: 20-30 minutes.For jumbo muffins: 35-45 minutesMuffins are done when a toothpick inserted into the center comes out clean. Remove pan to a wire rack and allow to cool completely before attempting to remove the muffins from the pan.