Add the butter to the bowl of a stand mixer and whisk until fluffy and lightened in color.
Add ⅓ of the sweetened condensed milk and whisk until incorporated. Continue adding the condensed milk and whisking until it is all incorporated before adding the next portion.
Finish by mixing in the salt and vanilla.
Melt the chocolates over a double boiler, remove from the heat, and let cool until room temperature and slightly thickened.
Add ⅓ of the melted chocolate and whisk until incorporated. Continue adding the chocolate and whisking until it is all incorporated before adding the next portion.
Finish by mixing in the salt and vanilla.
Add the sugar and water to a medium pot set over medium-high heat. Without stirring, let the sugar melt and caramelize. Once a light amber color, slowly and carefully stir in the warmed cream a little at a time. Once completely incorporated, continue cooking the caramel until it reaches 230F (110C). Remove from the heat and let cool until room temperature and slightly thickened.
Add ⅓ of the caramel and whisk until incorporated. Continue adding the caramel and whisking until it is all incorporated before adding the next portion.
Finish by mixing in the salt and vanilla.
