Preparation

Make the sauce

• Attach a candy thermometer to a 2-quart heavy-duty saucepan. Add the sugar, honey, and 1/4 cup water, and whisk to combine. Bring to a boil over medium-high heat, stirring occasionally and washing down the sides of the pan with a wet pastry brush, until the sugar dissolves, 3 to 5 minutes. Lower the heat to medium and boil vigorously without stirring until golden in spots and the candy thermometer reads 350°F, 5 to 10 minutes. As the mixture darkens in spots, swirl the pan gently to even out the color, but do not stir.
• Once it’s completely amber-colored, lower the heat to a simmer and add the cream in a slow, thin stream, whisking vigorously. The caramel will bubble up and may harden into a lump at first; continue whisking until smooth. Simmer for 3 minutes, whisking occasionally.
• Remove from the heat and stir in the vanilla and salt. Let cool to room temperature.

Make the panna cottas

• Lightly spray six 6- to 8-oz. ramekins, small bowls, or pastry molds with cooking spray.
• Put the cream in a 2-quart saucepan and sprinkle with the gelatin. Allow the gelatin to soften for about 5 minutes. Place the saucepan over low heat and whisk in the sugar until the gelatin and sugar are completely dissolved, 2 to 3 minutes. Rub a little between your fingers to check. (Avoid simmering, which destroys the gelatin’s thickening ability; if you see bubbles, remove from the heat and let it cool.)
• Off the heat, whisk in the buttermilk, vanilla and salt.
• Transfer the mixture to a large measuring cup and divide among the prepared ramekins. Cover loosely with plastic wrap. Refrigerate until set, 1 to 2 hours.
• Serve the panna cottas in their ramekins, or unmold: Moisten six serving plates with a little warm water (this makes it easier to center the panna cottas). Loosen the edges of a panna cotta with a fingertip, then slowly invert it onto a plate. Gently jiggle the ramekin side to side until the panna cotta slips out. Lift the ramekin, reposition the panna cotta on the plate, if needed, and pat the plate dry. Serve, chilled for a firm panna cotta or at room temperature for a softer one, with the sauce.

Make Ahead Tips

The sauce can be refrigerated, covered, for up to 3 months.

The panna cottas can be made 1 day ahead and refrigerated, covered.