1. Preheat oven to 350 degrees F.
2. Grease and floor muffin pan (or use paper liners). 3. Beat together butter, eggs, salt, and sugar.
4. Mix flour with baking powder and sift into first mixture, alternating with milk.
5. Blend in vanilla.
6. Add blueberries.
7. Pour into muffin pan and bake for 25 minutes.