How to Make It
Preheat the broiler on high and position a rack about 6 inches from the heat. In a large bowl, toss the peaches with the brown sugar and scrape them onto a rimmed baking sheet. Broil the peaches for about 15 minutes, flipping them halfway through, until caramelized and juicy. Let the peaches cool slightly. Lower the oven temperature to 375°.
Meanwhile, in a large bowl, combine the flour, granulated sugar, baking soda and salt. Add the butter and, with your fingers, rub it into the mixture evenly. Stir in the egg yolk and vanilla. Refrigerate the crumb topping.
In a bowl, toss the cooled peaches with the lemon juice; divide among six 8-ounce ramekins. Sprinkle with the crumb topping and bake until the topping is golden and the fruit is bubbling, about 20 minutes. Let cool for 5 minutes, then serve with the vanilla ice cream and a drizzle of the balsamic syrup.