Preheat oven to 350 degrees F (175 degrees C). Grease muffin cups or line with paper muffin liners.
In a medium bowl, combine flour, baking powder, baking soda and salt. In a large bowl, cream together butter and sugar until light and fluffy. Beat in the eggs one at a time, then stir in the vanilla extract. Beat in the flour mixture alternately with the orange juice, mixing just until incorporated. Fold in the walnuts.
Fill the prepared muffin cups about 2/3 full. Bake in preheated oven for 20 to 25 minutes, or until a toothpick inserted into the center of a muffin comes out clean.
Cool in the pans for 10 minutes before removing to cool completely on a wire rack.
Interesting Facts
Orange juice is a great way to add a citrusy flavor to baked goods.
Walnuts are a great source of healthy fats and protein.