Center a rack in the oven and preheat to 400 degrees F. Butter or spray the 12 cavities on a regular-size muffin pan or fit the cavities with paper muffin cups. (I used baker's spray).
Whisk together the flour, baking powder, baking soda, salt, and spices. Place the halved cranberries in a bowl and toss with a tablespoon of the flour mixture.
2 cups all purpose flour, 2 teaspoons baking powder, 1/4 teaspoon baking soda, 1/4 teaspoon salt, 3/4 teaspoon ground cinnamon, 1/2 teaspoon ground ginger, pinch of nutmeg, pinch of ground allspice, 1 cup frozen cranberries
Place the white chocolate chunks in another bowl and toss with a tablespoon of the flour mixture. Set aside.
4 ounces good quality white chocolate bar
Working with a stand mixer, preferably with a paddle attachment, or with a hand mixer in a large bowl, beat the butter at medium speed until soft. Add both the sugars and continue to beat until light and smooth.
8 Tablespoons unsalted butter, 1/2 cup granulated sugar, 1/4 cup light brown sugar
One by one, add the eggs, beating for a minute after the eggs are incorporated, then beat in the vanilla.
2 large eggs, 1/2 teaspoon pure vanilla extract
Lower the mixer speed and mix in the pumpkin and buttermilk. With the mixer at low speed, add the dry ingredients in a steady stream, mixing only until they disappear. To avoid overmixing, you can stop the machine early and stir any remaining dry ingredients into the batter using a rubber spatula.
3/4 cup canned unsweetened pumpkin puree, 1/4 cup buttermilk
Fold in the cranberries, then fold in the chocolate. Spoon batter into the prepared muffin pan. Place muffin pan on a cookie sheet.
Bake for about 25 minutes, or until a thin knife or toothpick inserted into the center of the muffins comes out clean. Transfer the pan to a cooling rack and cool the muffins for 5 minutes in the pan. Then, carefully remove each one from its cavity and finish cooling on the rack.
I've made these muffins with pureed fresh pumpkin I had stashed in my freezer in previous years, and I've also made them with canned pumpkin. Both ways are great!
Keep the cranberries in the freezer until you have measured out all the other ingredients. There's no need to put them back in the freezer after that.
As with all quick breads and muffins, be careful not to over-mix the batter as the gluten will develop, causing the muffins to become tough.