Prepare the Gelatin:

1. Dissolve the Gelatin: In a small bowl, sprinkle the gelatin over 1/4 cup of cold milk. Let it sit for about 5 minutes to bloom (soften and absorb the liquid).

Cook the Cream Mixture:

2. Heat the Cream and Milk: In a medium saucepan, combine the heavy cream, remaining milk, and sugar. Place it over medium heat and stir occasionally until the sugar is fully dissolved and the mixture is hot, but not boiling.
3. Add the Coffee and Gelatin: Once the cream mixture is hot, remove it from the heat. Stir in the brewed coffee, bloomed gelatin, vanilla extract, and salt. Continue stirring until the gelatin is completely dissolved and the mixture is smooth.

Chill the Panna Cotta:

4. Pour into Molds: Pour the panna cotta mixture into individual serving cups or molds. Let them cool to room temperature, then cover with plastic wrap and refrigerate for 3-4 hours, or until set.

Prepare the Caramel Topping:

5. Warm the Caramel Sauce: If using store-bought caramel sauce, warm it slightly in the microwave or over low heat to make it pourable.
6. Top the Panna Cotta: Once the panna cotta has set, drizzle the warm caramel sauce over the top of each serving. You can also add a pinch of sea salt on top for extra flavor.