Prepare the loaf pan. Preheat the oven to 350°F (175°C). Grease a 9 × 5-inch loaf pan and line it with parchment paper, leaving a little overhang on the sides to make removing the cake easier.
Mix the wet ingredients. In a large mixing bowl, whisk together the canola oil and granulated sugar until combined. Whisk in the eggs one at a time, followed by the vanilla extract. Mix until the mixture is smooth and slightly thickened. Stir in the sour cream until the wet ingredients are evenly combined.
Combine the dry ingredients. In a separate medium bowl, whisk together the flour, hojicha powder, baking powder, baking soda and salt. Add the dry ingredients to the wet mixture. Gently fold with a spatula until the flour is almost incorporated. Avoid overmixing, as this can make the cake dense. Fold the white chocolate chips into the batter until evenly distributed. Pour the batter into the prepared loaf pan.
Bake the loaf. Bake for 55 minutes or until a toothpick inserted into the centre comes out clean or with a few moist crumbs. Oven temperatures can vary. Let the loaf cool in the pan for about 10 minutes before lifting it out using the parchment paper.
