Heat oat milk gently in a saucepan over low heat.
Add caramel syrup, toffee syrup, brown sugar, and sea salt.
Stir continuously for 1–2 minutes until fully dissolved.
Remove from heat and mix in vanilla extract.
Fill two tall glasses with ice cubes.
Pour chilled brewed coffee evenly into each glass.
Add vanilla toffee caramel milk mixture on top.
Stir gently before sipping, or enjoy layered elegance first.