An easy and delicious cake that tastes like a blueberry muffin.
Preheat the oven to 350 degrees F. Grease and flour a 9-inch by 13-inch baking pan.
Cream together the butter and sugar. Add the egg and beat well. Dissolve the soda in the milk. Sift together the flour and cream of tartar. Add the flour mixture to the butter mixture alternately with the milk, beating well after each addition. Add the lemon juice and vanilla extract. Fold in the berries. Spoon into the baking pan.
Bake for about 45 minutes. Serve warm or completely cooled, directly out of the pan.