In a saucepan, combine berries and sugar.Place over medium to low heat. Stir util berries cook into a sauce, about 15 minutes or so
Butter a 8x5x3 inch loaf pan
Trim crust from the bread slices, and butter generously on only one side
Spoon a little of the sauce into the bottom of the loaf pan. Top with 2 slices of the bread, butter side up, fitting them so they cover the bottom of the pan.
Spoon blueberry sauce over, using about 1/3 cup to top each slice of bread. Top with two more slices of bread. Repeat until all the bread and blueberry sauce is used up, ending with the blueberry sauce. Cover
Bake for 15 minutes at 350 F
Remove from oven and chill overnight
To serve, run knife around edges of pan to loosen and invert onto a plate. Cut into slices, and serve with whipped cream topping each slice. Garnish with additional berries, if you desire.