1. In a bowl, sift the flour, baking powder, and salt. Set aside.
2. Cut the apples into pieces and beat with a food processor until they are finely chopped.
3. Add the egg, brown sugar, milk, vanilla, and oil and mix again.
4. Pour the liquid mixture over the dry ingredients, beating as little as possible, just enough to obtain a wet batter.
5. Pour into muffin molds and bake at 350°F for about 20-30 minutes, or until a wooden stick comes out clean.