In a medium heatproof bowl, combine chocolate, vanilla, and salt.
In a small saucepan, heat cream over medium heat until just boiling. Pour hot cream over chocolate mixture; whisk until melted and smooth. Refrigerate for 1 hour.
Transfer chocolate mixture to the bowl of a stand mixer fitted with the whisk attachment. Beat at medium speed until light and fluffy, about 3 minutes. Use immediately.
Recipe by Bake from Scratch at https://staging.bakefromscratch.com/milk-chocolate-layer-cake/