Pre-heat oven to 200°. Trim the bottom crust from the Panettone. Starting at the bottom of the loaf, cut it crosswise into 6 (3/4-inch thick) round slices. (Reserve the top piece for buttered toast!) In a large bowl, whisk the eggs. Add the cream, milk and sugar, and whisk until well blended.

Melt 1 tablespoon butter on a nonstick griddle over medium heat. Dip the Panettone into the egg mixture, turning to allow both sides to absorb it. Grill the soaked Panettone slices until golden brown and firm to the touch, about 4 minutes per side. Transfer to a baking sheet and keep warm in the oven. Repeat with the remaining butter, Panettone slices and egg mixture.

Transfer the French toast to plates. Top each with a dollop of mascarpone, and sprinkle with powdered sugar and cinnamon. Add berries, drizzle with maple syrup, and serve immediately.