Combine 1/2 cup sugar and 3 tablespoons butter in a saucepan over low heat; cook and stir until butter is melted, 3 to 4 minutes. Stir cream into butter mixture; bring to a boil, reduce heat, and simmer until golden sauce is slightly thickened, 5 to 10 minutes. Pour golden sauce into a bowl and cover with plastic wrap.
Preheat oven to 350 degrees F (175 degrees C).
Beat 3/4 cup sugar and 3 tablespoons softened butter together in a bowl using an electric mixer until smooth and creamy. Add eggs and vanilla extract; beat until fluffy, 2 to 3 minutes. Slowly pour milk into butter-egg mixture while continuing to stir until evenly combined.
Preheat oven to 350 degrees F (175 degrees C).
Place bread cubes in a large bowl. Pour milk mixture over bread; let stand until bread is moistened, about 5 minutes. Fold blueberries into bread mixture; transfer to a 3-quart baking dish.
Mix 2 tablespoons sugar and cinnamon together in a bowl; sprinkle over bread mixture. Drizzle 1/3 cup golden sauce over bread mixture.
Bake in the preheated oven until a knife inserted in the center of the bread pudding comes out clean, about 35 minutes. Serve bread pudding with remaining golden sauce.
