Preheat the oven to 350°F. Grease the inside of a 12-cup Bundt pan with vegetable shortening. Dust the inside of the pan with gluten-free flour, making sure to shake out any excess flour.

In a medium-sized bowl, stir together the gluten-free flour, baking powder, and baking soda.

In the bowl of a stand mixer, add the softened butter, vegetable oil, sugar, and sour cream. Beat on medium speed for 4 minutes, scraping down the sides of the bowl as needed.

Add the eggs one at a time, beating until each egg is thoroughly incorporated. Scrape down the sides of the bowl between each addition.

Turn the mixer to low and gradually add the flour mixture, mixing until just combined. Scrape down the sides of the bowl as needed to make sure all of the flour is incorporated.

Add the chopped apples, golden raisins, and raisins. Stir gently to combine.

In a small bowl, mix together the 1/4 cup sugar and cinnamon.

Pour half of the batter into the prepared Bundt pan and smooth the top. Sprinkle half of the cinnamon-sugar mixture evenly over the batter.

Pour the remaining batter into the pan and smooth the top. Sprinkle the remaining cinnamon-sugar mixture over the batter.

Bake for 65–70 minutes, or until a toothpick inserted into the center comes out clean.

Remove the cake from the oven and place the Bundt pan on a wire rack. Allow the cake to cool in the pan for 20 minutes. The cake should begin to pull away from the sides of the pan.

Turn the cake out onto a cake plate and allow it to continue cooling.

Once cooled, dust the top of the cake with confectioner's sugar.

Slice and serve.