1. Preheat oven to 200°.
2. Place a large shallow baking dish in oven to warm.
3. Combine first 7 ingredients (through salt) in a large bowl, stirring well with a whisk. (You should have about 2 cups batter.) Place 2 slices of bread in batter; soak 1-2 minutes.
4. Heat a large nonstick skillet over medium heat; coat pan with cooking spray. Remove bread slices from the batter; drain slightly. Place bread in skillet; cook until golden (2-3 minutes on each side), flipping once. Transfer toast to warm baking dish in oven. Repeat steps with the remaining bread slices.
5. Place 2 slices of French toast on 4 plates. Sprinkle each plate with 1/2 teaspoon powdered sugar; top with 1/4 cup each of blueberries and raspberries. Drizzle each plate with 2 teaspoons maple syrup before serving.