Cranberry White Chocolate Muffins

1/2 cup unsalted butter (1 stick), softened
1/2 cup granulated sugar
1/4 cup light brown sugar, packed
2 large eggs
1/2 cup sour cream or Greek yogurt (lite versions are okay)
2 tablespoons buttermilk (buttermilk recommended, but regular milk or cream may be substituted)
2 teaspoons vanilla extract
1 1/2 cups all-purpose flour
1 teaspoon baking soda
1 teaspoon baking powder
1/2 teaspoon ground cinnamon
pinch salt, optional and to taste
1 cup white chocolate chips
1 1/4 cups fresh cranberries, plus more for sprinkling (frozen may be substituted, do not thaw if using frozen)