1. Heat oven to 375 degrees
2. Grease 18 regular-size muffin cups (or 12 large size muffin cups)
3. In bowl, mix butter until creamy. Add sugar and beat until pale and fluffy.
4. Add eggs, one at a time, beating after each addition.
5. Beat in vanilla, baking powder and salt.
6. With spoon, fold in half of flour, then half of milk into batter; repeat.
7. Fold in aronia berries
8. Spoon into muffin cups and sprinkle a dash of nutmeg onto each muffin.
9. Bake 15 to 20 minutes, until golden brown and springy to touch