Adjust an oven rack to the middle position, and preheat oven to 400F. Line an 8 x 4-inch loaf pan or Pullman pan with parchment paper, allowing 1-inch wings to hang over the edges on the long sides.

In a food processor, combine the flour, baking powder, salt, 1/4 cup sugar, and orange zest and pulse to combine. Add the butter cubes and pulse until the butter is in the size of peas. Transfer the mixture to a large bowl.

In a liquid measuring cup or small bowl, whisk together the eggs, cream, orange juice, and vanilla and add to the dry ingredients. Use a wooden spoon or spatula to stir until just combined. Add the chocolate chips and candied orange zest (if using) near the end of stirring, just before mixture is fully combined, and mix them gently into the batter.

Pour the mixture into the prepared loaf pan and spread it out evenly. Brush lightly with heavy cream, and then sprinkle the top with the remaining 1 teaspoon sugar. Bake until golden brown on top and a toothpick inserted into the center comes out clean, 35-45 minutes.

Cool in the pan on a wire rack for 10 minutes. Using the parchment wings, remove to the rack to cool completely. Slice with a serrated knife and serve.