In a medium saucepan over low heat, combine sweetened condensed milk, caramel sauce, unsalted butter, and vanilla extract. Stir continuously for 3-5 minutes until smooth and creamy.

Remove from heat and add semi-sweet chocolate chips. Stir vigorously until fully melted and fudge thickens, about 2-3 minutes.

Line an 8x8 inch baking dish with parchment paper and pour in the fudge mixture, spreading evenly. Chill in the refrigerator for about 1-2 hours.

Cut the chilled fudge into small squares and roll into 1-inch diameter balls, placing each on a parchment-lined tray. Chill for an additional 15 minutes.

Melt couverture or melting chocolate in a microwave-safe bowl in 30-second intervals until smooth. Allow to cool slightly.

Dip each chilled truffle into the melted chocolate and place back on parchment paper.

Sprinkle each truffle with flaky sea salt and drizzle with caramel sauce if desired.

Let the coating set at room temperature for 20-30 minutes or refrigerate for quicker results. Store in an airtight container.