Preheat the oven to 350 degrees F. For the muffins, cream together the butter and sugar. Add the eggs and vanilla extract and beat. Sift the dry ingredients and add them to the butter and eggs mixture alternately with the orange juice. Fold in the apples and the nuts.
Mix all the topping ingredients together in a small bowl and sprinkle on top of the muffins. Bake in greased or paper-lined muffin tins for 25 minutes.