Cut the bread into large 2 inch cubes. Scatter over the brown sugar in the bakind dish.
In a saucepan, warm the milk, the 2 tbsp of butter, vanilla, white sugar and pinch of salt just until the butter melts. Don't heat too much so eggs don't curdle. Remove from stove, add the eggs and whisk to combine.
Pour this milk mixture evenly onto the bread cubes, and leave to soak for an hour or so. Near the end of the soaking time, heat the oven to 180C (350F). Scatter the flaked almonds on top if using.
Bake for 30-35 minutes or until puffy and golden brown. Remove from the oven, dust icing sugar on top and serve warm.