Make the salted caramel

1. Heat the sugar in a small saucepan over medium heat until fully melted and amber.
2. Add the butter and stir until smooth.
3. Whisk in the cream in 2–3 additions; cook 2–3 minutes until slightly thick.
4. Add the salt, blend to smooth if needed, and let cool completely.

Make the salted caramel ganache

1. Place the chopped white chocolate in a heatproof bowl.
2. Add the cooled salted caramel and vanilla.
3. Heat half of the heavy cream until simmering, then pour it over the chocolate.
4. Let sit a few seconds, then stir until melted and smooth.
5. Add the cold cream and mix again.
6. Blend with an immersion blender, cover with plastic wrap touching the surface, and refrigerate 3–4 hours.
7. Whip at low to medium speed until thick, creamy, and stable.
8. Use immediately to fill cakes or pipe on cupcakes.