Preheat oven to 425°F (220°C). Line a 12-cup muffin tin with paper liners and lightly grease them.

In a large bowl, whisk together the flour, granulated sugar, brown sugar, baking powder, baking soda, and salt.

Take 2 tablespoons of this dry mixture and toss it in a small bowl with the raspberries and white chocolate chips. Set aside.

In a medium bowl, whisk together the buttermilk, oil, melted butter, eggs, and vanilla extract until smooth.

Pour the wet ingredients into the dry ingredients. Gently fold with a rubber spatula until just combined. Do not overmix.

Gently fold in the flour-coated raspberries and white chocolate chips.

Let the batter rest uncovered for 15 minutes.

Divide the batter evenly among the muffin cups, filling them all the way to the top.

Bake at 425°F for 5 minutes. Keeping the oven door closed, reduce the oven temperature to 350°F (175°C) and bake for an additional 15-18 minutes, or until a toothpick inserted into the center comes out clean.

Cool in the pan for 5 minutes before transferring to a wire rack to cool completely.