Prepare sauce. In a medium saucepan combine butter and sugar. Cook and stir over low heat until butter is melted. Stir in cognac and heavy cream. Bring to a boil, reduce heat, simmer for 8 minutes until it slightly thickens. Refrigerate sauce if not using within two hours.

In a large bowl beat butter and 3/4 cup of sugar on medium/high speed until well combined.

Add eggs and vanilla, beat for 3 minutes. Slowly stir in milk.

Place bread in a large bowl. Pour milk mixture over bread and let stand for at least 5 minutes. Stir in blueberries carefully.

Transfer to ungreased 3-qt rectangular baking dish.

Sprinkle the turbinado sugar and cinnamon over bread mixture. Drizzle 1/3 cup of sauce over the mixture.

Bake for 35 minutes or until a knife comes out clean. Serve warm with warm sauce.