Preheat your oven to 175°C (350°F) and grease your loaf pan with butter, then dust lightly with flour to prevent sticking.
Zest both oranges using a microplane, aiming to only grate the bright orange outer layer—this will release fragrant oils that flavor the batter.
Cut the oranges in half and squeeze out about ½ cup of fresh juice, straining out any seeds or pulp to keep the batter smooth.
In a large mixing bowl, beat the softened butter until creamy and light, about 2-3 minutes, using an electric mixer or whisk.
Gradually add the sugar to the butter and continue beating until the mixture is fluffy and pale, about 3 minutes.
Add the eggs one at a time, beating well after each addition, ensuring each egg is fully incorporated before adding the next.
Pour in the orange juice and fold in the orange zest, mixing until the batter is fragrant and smooth.
In a separate bowl, sift together the flour and baking powder, then gradually fold this into the wet ingredients, mixing just until combined to keep the batter airy.
Pour the batter into the prepared loaf pan, smoothing the top with a spatula, and gently tap the pan on the counter to remove any air bubbles.
Bake in the preheated oven for 50-60 minutes, or until the top is golden brown and a toothpick inserted into the center comes out clean.
Let the cake cool in the pan for about 15 minutes, then transfer it to a wire rack to cool completely before slicing and serving.
