For French toast, whisk eggs, milk, vanilla, cinnamon & nutmeg together. Heat a griddle or non-stick pan over medium heat. Dip bread slices into egg mixture and place on greased griddle and cook until golden, about 3 minutes. Flip toast over and cook until other side is golden and set aside to cool. Cut up French toast into 1 ½-inch pieces.
Preheat oven to 350 °F and grease an 8-cup baking dish. Layer diced French toast with banana slices and sprinklings of raisins. Whisk eggs, and egg yolk, then whisk in maple syrup, milk, yogurt and vanilla. Pour mixture over diced French toast in dish and press down gently to help egg mixture to soak in, and let sit 2 minutes. Sprinkle top with a little sugar and place baking dish in a large pan, with at least 2-inch sides. Pour hot water around baking dish and bake strata for 75 to 85 minutes, until center springs back when gently pressed. Let strata sit for 10 minutes before serving.
Bread pudding can be served warm, chilled or at room temperature, with a little drizzle of maple syrup and a dollop of yogurt.