If the cornbread is still soft and moist, place the cornbread cubes on a baking sheet or pizza pan and bake until dry (about an hour). If you started with stake cornbread, skip this step.
Raise oven to 325 degrees. Grease a 10 x 12-inch baking pan.
In a large bowl, combine sugar, cinnamon, milk, cream, eggs, yolks and vanilla. Add the corn bread, blueberries and pistachios (or almonds) and stir it all gently. This step is finished when the biggest cornbread chunks still are a little dry in their centers.
Pour the cornbread mixture into the baking pan. It should have cracks and open areas. Cover with aluminum foil and bake for an hour. Remove the foil cover and continue baking for about 25 minutes more, until the top of the pudding is golden brown. Remove it from the oven to cool.
In a medium saucepan off the heat, stir the 2 Tbs. of sugar and cornstarch together until blended. Add the frozen berries and toss until coated with the sugar-cornstarch mixture. Cover the pan and cook over low heat. The blueberries will melt and slowly become a thick, bubbling sauce.
Drizzle the sauce over the baked blueberry pudding. But into three-inch squares and serve, warm or at room temperature.