Preheat your oven to 350°F (175°C). Grease and flour a 9x5 inch loaf pan.

In a mixing bowl, cream together the softened butter and sugar until it is light and fluffy.

Add the eggs one by one, mixing well after each addition.

In another bowl, combine the flour, baking powder, and salt. Gradually add this dry mixture to the butter mixture alternating with milk, and mix until just combined.

Stir in the lemon and orange zest, juice, and vanilla extract.

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

Bake for about 60 minutes, or until a toothpick inserted in the center comes out clean.

Allow to cool in the pan for 10 minutes, then remove from the pan and cool on a wire rack.

Serve warm or at room temperature, optionally drizzled with a simple lemon-or-orange glaze.