Preheat oven to 450 degrees F. Grease a 9x13-inch baking pan.
Slice the bread into 12 to 14 slices about 1/4 inch thick; place on an ungreased cookie sheet. Whisk eggs, milk, baking powder, and vanilla extract together; slowly pour mixture over the bread, turning to coat the bread completely. Cover with plastic wrap and refrigerate for 1 to 2 hours or overnight.
Combine blueberries (don't defrost frozen fruit), chopped nuts, cinnamon, sugar, and cornstarch and then place into prepared baking pan. Place bread (wettest side up) on the berry mixture. Wedge slices in tightly, cutting some pieces to fit, if necessary. Brush tops of bread with melted butter.
Bake 20 to 25 minutes or until the toast is golden and the berries are bubbling around the sides. Remove from the oven and sprinkle with powdered sugar.
Let sit for 5 minutes before serving. Serve by turning the bread over so it is topped with the blueberry sauce.
NOTE: I've made this with raspberries, peaches, and strawberries. I believe that almost any fruit can be used that generates juice. If the recipe is cut in half, half all ingredients except the baking powder.
Makes 4 to 6 servings.
* Select plump and full blueberries with a light gray-blue color. Blueberries with any hint of red are not fully ripened. Once blueberries are picked, they will not ripen any further. Do not wash the blueberries until just before eating or using in your recipes to prevent berries from becoming mushy. Unwashed blueberries will stay fresh for up to two weeks in the refrigerator if kept dry.
Baked French Toast with Blueberry Sauce Recipe: https://whatscookingamerica.net/bread/blueberryfrench.htm