Preheat oven to 350 degrees F. Spray a 8.5 x 4.5-inch loaf pan with cooking spray and set aside.

In the bowl of a stand mixer, combine flour, sugar, baking powder, baking soda and salt. Add the cold butter and mix on low until the butter is incorporated into the flour.

In a separate bowl, whisk together egg, buttermilk, sour cream and orange zest. Gradually add the egg mixture to the dry ingredients. Stir in the raisins and caraway seeds.

Transfer to the prepared loaf pan. The dough will be very sticky, so it helps to dampen your fingers or spatula with a little bit of water so that you can spread the dough in the pan without too much sticking.

Bake for 35-45 minutes, or until a toothpick inserted in the center comes out clean.

Remove from pan and cool completely on a wire rack before slicing.