Preheat your oven to 350°F. While it heats, cut the brioche into 1-inch cubes and place them in a large bowl. In a separate medium bowl, whisk together the eggs, half and half, vanilla, cinnamon, nutmeg, lemon juice, and salt until well combined and smooth. The lemon juice adds brightness that cuts through the richness of the custard and complements the peaches beautifully.

Add the sliced peaches to the bowl with the brioche cubes and gently toss to distribute them evenly throughout. Pour the custard mixture over the bread and peaches, then fold everything together with a spatula until all the bread pieces are well coated and the custard is evenly distributed. Don't overmix—gentle folding ensures the bread maintains some texture while still absorbing the custard.

Pour the bread and custard mixture into a greased 9x13 inch baking dish, spreading it in an even layer. While the mixture settles, make the cobbler topping by combining the flour, brown sugar, and cinnamon in a small bowl. Add the chilled butter pieces and use your fingertips or a fork to work the butter into the flour mixture until it resembles coarse crumbs with pea-sized pieces throughout. I find this texture gives the cobbler topping the perfect balance of crunch and tenderness.

Sprinkle the crumb topping evenly over the bread and peach mixture, breaking up any large clumps as you go. Bake for 45 to 60 minutes, until the top is golden brown and a knife inserted into the center of the bake comes out clean. The custard should be set but still slightly jiggly in the very center—this keeps the bake moist and custardy rather than dry.

Remove the bake from the oven and let it rest for 10 minutes before serving. This brief rest allows the custard to set up a bit more, making it easier to cut into neat portions. Dust generously with powdered sugar just before serving for a beautiful finish and extra sweetness.