Preheat oven to 375 degrees.
Mix together flour, salt, baking soda, and baking powder in large bowl
In separate bowl, beat butter, sugar, eggs and vanilla. Add in apples, then slowly blend in flour mixture
Put in 12 greased muffin pans.
Add topping to the top of muffins.
Bake 20 minutes.
Once cooled, freeze in freezer bags for up to 6 months.