Line a baking sheet with parchment paper. In a medium pot, cook the sugar over medium heat, stirring occasionally with a heat-proof spatula until the sugar has melted and turns a golden caramel, about 8 minutes. Remove from the heat and carefully pour the caramel onto the prepared baking sheet. Spread in a thin, even layer and sprinkle with flaky sea salt. Let sit 5 minutes. Once hardened, crush the caramel into small pieces/shards with the back of a spoon. Combine the milk, caramel, and a pinch of salt in a medium pot and bring to a simmer, heat until steaming. Add the vanilla. Using a small whisk or a fork, whisk until frothy. Remove from the heat. Divide the espresso between 2 mugs. Pour over the caramel milk. Top with whipped cream and a sprinkle of caramel brûlée Drink up!