How to Make It
Preheat the oven to 350°. In a small bowl, mix 1 tablespoon of the sugar with the hot water, stirring to dissolve the sugar. Add 2 tablespoons of the olive oil and stir to combine.
Arrange the bread cubes on a large rimmed baking sheet. Drizzle the bread cubes with the sugar-syrup-and-olive-oil mixture and toss to coat. Bake until the bread cubes are crisp and golden brown, about 10 minutes.
Meanwhile, in a medium stainless steel bowl, whisk the egg yolks with the remaining 1/4 cup of sugar and 3/4 cup of Moscato. Fill a large bowl with ice water. Set the bowl with the eggs over a medium saucepan filled with 1 inch of barely simmering water (you can also use a double boiler).
Remove the zabaglione from the heat and whisk in the remaining 1 tablespoon of olive oil. Carefully set the bowl in the ice bath and whisk the zabaglione until chilled, about 5 minutes.
To serve, add the bread cubes and mint to the fruit in the bowl and toss well. Transfer the panzanella to shallow bowls, top each one with a large dollop of zabaglione and serve right away.