Make the salted caramel: Add sugar and water to a medium saucepan over medium heat. Swirl the pan gently (do not stir) until sugar dissolves and turns a deep amber color, about 6-8 minutes. Watch closely to prevent burning.
Remove from heat and carefully whisk in the warm heavy cream — it will bubble vigorously. Stir in the butter and sea salt until smooth. Let cool for 5 minutes. The sauce will thicken as it cools.
Brew two shots of espresso or prepare 1/2 cup of strong coffee. Pour into your favorite mug.
Add 2 tablespoons of the salted caramel sauce to the hot espresso and stir until completely combined.
Heat the milk in a small saucepan or microwave until steaming but not boiling, about 150-160°F. Froth using a milk frother, French press, or whisk vigorously for 30 seconds until foamy.
Pour the frothed milk over the caramel espresso, holding back the foam with a spoon. Spoon the remaining foam on top.
Drizzle with extra caramel sauce and sprinkle with a pinch of flaky sea salt. Serve immediately and enjoy.
