Preheat the oven to 425℉ and coat a baking sheet with nonstick spray or grease with butter. If you line it with parchment paper, as I've done, be sure to give it a light, nonstick spray, too.
For the berries
In a medium bowl, toss the berries with honey and a pinch of salt. Let sit for 15 to 20 minutes while making the French toast.
For the French toast
Whisk together the eggs, milk, melted butter, vanilla, honey, cinnamon, nutmeg, and salt in a medium bowl. Dip one slice of bread into the egg mixture and turn to coat. Let excess drip off the slice and place it on the prepared baking sheet. Repeat with remaining slices.
Bake for 10 minutes, then flip the slices over using a spatula. Bake for another 10 minutes or until lightly golden.
For the mascarpone
Whip the mascarpone until creamy. Drizzle in the honey, add lemon zest, and stir to combine.
To serve
To serve, place one or two slices of French toast on each plate. Dollop with whipped mascarpone, spoon berries with their juice over the top. Drizzle with honey if desired.