Beat the butter until completely smooth, pale, and creamy. No aeration is needed—focus on silkiness, not volume.
Add the condensed milk slowly, in 2–3 additions, beating just until fully emulsified and glossy after each addition.
Add vanilla extract and salt. Mix for 10–15 seconds only, just until perfectly combined.
Buttercream is ready to pipe, frost, decorate, or spread.
