Preheat oven to 400°F. Line a 12-cup muffin tin with paper liners or spray with nonstick baking spray.
In a medium bowl, whisk together the flour, baking powder, baking soda, and salt.
In a large bowl, whisk together the oil, sugar, eggs, sour cream, and vanilla extract until smooth and fully combined.
Add the dry ingredients to the wet ingredients and mix gently until just combined - do not overmix.
Fold in the raspberries and white chocolate carefully.
Divide the batter evenly among the muffin cups, filling almost to the top. Sprinkle with coarse sugar if using.
Bake for 5 minutes at 400°F, then reduce heat to 350°F and bake for an additional 13–15 minutes, or until the muffins are golden and a toothpick comes out with just a few moist crumbs.
Cool in the pan for 5 minutes, then transfer to a wire rack to cool completely.