I happened to be almost out of white flour (how did that happen?) so I substituted wheat flour for part of it. That made it healthier and still tasty, but you can use all white flour if you like. The recipe says to use a 13"x9"x2" pan, but also says it yields 8 servings. Those would be 8 monster sized servings! I compromised with an 8"x12" pan and more servings. The cake seemed to fit that pan size well.
1/4 cup butter
1 cup white sugar
1 tsp baking soda
1/2 cup milk
1 1/2 cup white flour
1 cup wheat flour
2 tsp cream of tartar
1 tsp lemon juice
1 tsp vanilla extract
1 pint blueberries
Preheat oven to 350 degrees. Grease and flour an 8"x12" pan.
Cream together the butter and sugar. Add the egg and beat well.
Dissolve the baking soda in the milk.
Add flours and cream of tartar to butter mixture alternately with milk, beating well after each addition.
Add the lemon juice and vanilla extract. Fold in the berries.
Spoon into the baking pan.
Bake for 45 minutes or until toothpick in center comes out clean.
Serve warm or completely cooled, directly out of pan.