Blueberry Muffins/Cake

I got the original recipe from a B&B in Bar Harbor Maine over 20 yrs ago. You can make either muffins or a cake. This is my version.
1 1/2 cups unbleached all purpose flour
1 TSP baking powder
1/2 TSP salt
1/2 cup unsalted butter, softened
1 1/2 cups fresh blueberries tossed with 1 TBL flour
2 X-Lrg eggs
1/3 cup milk
1 TSP vanilla
1 cup sugar
Directions:
Preheat oven to 350.
Blend together butter, sugar, eggs and vanilla until fluffy. Blend together all dry ingredients. Add flour mixture alternating with milk into the butter mixture. Mix just until combined. Fold in blueberries. Fill muffins cups 2/3 full.
Bake for 30-40 minutes until lightly browned and tester comes out clean.
Makes 6 jumbo or 12 reg muffins.
For a blueberry cake spread the batter into a 8×8 pan.