1. Line a 9×9-inch baking dish with parchment paper, leaving some overhang for easy removal.
2. In a medium heatproof bowl, combine the semi-sweet chocolate chips, sweetened condensed milk, and softened butter.
3. Set the bowl over a pot of simmering water (double boiler method), stirring constantly until the chocolate is melted and the mixture is smooth—this usually takes about 5 minutes. Be patient and keep the heat gentle; I learned early on that rushing this step can cause the chocolate to seize, turning your smooth fudge into a grainy mess.
4. Remove the bowl from the heat and stir in the vanilla extract and 1/2 teaspoon flaky sea salt until fully incorporated.
5. Pour half of the fudge mixture into the prepared baking dish and spread it evenly with a spatula.
6. Drizzle the caramel sauce over the fudge layer, then use a knife or skewer to gently swirl it through for a marbled effect.
7. Pour the remaining fudge mixture over the caramel and smooth it out evenly.
8. If using, sprinkle the chopped toasted nuts on top for some added crunch and nutty flavor.
9. Sprinkle a pinch of flaky sea salt over the top to enhance the salted caramel contrast.
10. Refrigerate the truffles for at least 3 hours or until firm enough to cut into squares.
11. Once set, use the parchment overhang to lift the fudge from the dish and cut into 20 evenly sized squares.
12. For bite-sized truffles, roll the squares into balls between your palms and refrigerate again for 30 minutes to firm up.

One of my favorite tips is to make these truffles ahead of time—during a weekend afternoon when Maya is out with Eli, I can focus and get them chilling in the fridge, ready to be enjoyed all week. It’s a little luxury that brings simple joy to our busy family life.