Preheat your oven to 350°F/180°C. Grease and line a 9x5 inch loaf pan with parchment paper.
In a large mixing bowl, beat the butter and sugar together until light and fluffy. This should take about 3-5 minutes. You can use a stand mixer, hand mixer, or whisk.
Sift in all-purpose flour, baking powder, and salt. Mix until just combined.
In another bowl, mix eggs, milk, vanilla extract, and orange extract till well combined.
Add the liquid mix to the dry mix in 2-3 parts while mixing between each addition. Mix till well combined.
Transfer 3/8 part of the batter into another bowl. Add cocoa powder and ground cinnamon. Mix with a spatula till well combined.
Pour half of the vanilla batter into the prepared loaf pan. Pour half of the chocolate-cinnamon batter over the vanilla batter. Add the remaining vanilla batter and top with the rest of the chocolate-cinnamon batter.
Use a knife or skewer to gently swirl the batters together to create a marble effect. Be careful not to overmix.
Bake for 55-60 minutes, or until a toothpick inserted into the center comes out clean. If the top is browning too quickly, cover it loosely with aluminum foil.
Allow the cake to cool in the pan for about 10 minutes before transferring it to a wire rack to cool completely.
Drizzle melted white chocolate and dark chocolate on top. Refrigerate for 20 minutes. Slice and enjoy!