If Making Homemade Salted Caramel Sauce:

1. Cook the sugar: In a medium saucepan over medium heat, pour the granulated sugar in an even layer. Heat without stirring until the sugar begins to melt around the edges, about 4-5 minutes. Once it starts melting, gently whisk to encourage even melting and prevent burning. Continue cooking and whisking until all sugar is melted and the caramel turns a deep amber color, about 8-10 minutes total.
2. Add the butter: Carefully add the butter pieces (mixture will bubble vigorously). Whisk until butter is completely melted and incorporated, about 1 minute.
3. Add cream and salt: Remove from heat and slowly pour in the heavy cream while whisking constantly (it will bubble up dramatically). Whisk until smooth. Add the sea salt and whisk to combine. Let cool to room temperature, then transfer to a jar. This makes about 1½ cups of sauce, which you can store refrigerated for up to 2 weeks.

For the Milkshake:

4. Prepare your glasses: If desired, drizzle salted caramel sauce inside two tall glasses in a decorative pattern, creating swirls along the inside. Place glasses in the freezer while you make the shake.
5. Blend the shake: Add the vanilla ice cream, whole milk, ⅓ cup salted caramel sauce, sea salt, and vanilla extract to a high-powered blender. If you want an extra-thick shake, add 3-4 ice cubes as well.
6. Achieve perfect consistency: Blend on low speed initially to break up the ice cream, then increase to medium-high speed. Blend for 30-45 seconds until completely smooth and creamy. The shake should be thick enough to coat a spoon but still pourable. If too thick, add 1-2 tablespoons more milk and pulse briefly. If too thin, add another scoop of ice cream and blend again.
7. Taste and adjust: Sample your shake and adjust the salt level if desired. Remember, you can always add more salt but can’t take it away!
8. Serve immediately: Pour the milkshake into your prepared chilled glasses. The shake should be thick and hold its shape slightly when poured.
9. Add toppings: Top generously with whipped cream, drizzle with additional salted caramel sauce, and finish with a pinch of flaky sea salt. For extra decadence, add caramel candies, toffee bits, or crushed pretzels on top.
10. Serve right away: Serve immediately with extra-wide straws or long spoons. Milkshakes are best enjoyed fresh and will begin to melt and separate if left sitting too long.