Preheat the oven to 350°F and grease a loaf pan.
Blend the whole orange (with peel) until smooth.
Cream butter and sugar until fluffy.
Add eggs and vanilla, mix well.
Stir in the blended orange.
In another bowl, whisk together flour, baking powder, baking soda, and salt.
Add dry ingredients to wet, stir until just combined.
Pour into loaf pan and bake for 40-45 minutes, or until toothpick comes out clean.
Let cool before slicing.