Preheat your oven to 350°F (175°C). Grease the loaf pan with butter or cooking spray.

In a large mixing bowl, whisk together the flour, sugar, baking powder, and salt until well combined.

In a separate bowl, mix the melted butter, milk, eggs, and vanilla extract. Stir until the mixture is smooth.

Pour the wet ingredients into the dry ingredients and gently fold with a rubber spatula until just combined. Do not overmix.

Carefully fold in the chopped cranberries, walnuts (if using), and orange zest (if using) into the batter.

Pour the batter into the prepared loaf pan and smooth the top with the spatula.

Bake in the preheated oven for 50-60 minutes or until a toothpick inserted into the center comes out clean.

Once baked, remove the bread from the oven and let it cool in the pan for about 10 minutes. Then transfer it to a wire rack to cool completely.

For added sweetness, you can drizzle a simple glaze made of powdered sugar and orange juice over the cooled bread.

Store any leftovers in an airtight container at room temperature for up to 3 days. It can also be frozen for up to 3 months.