Preparation

Make the sauce

• In a 2-quart saucepan, bring the blueberries, sugar, lemon zest, and 1/4 cup water to a boil over medium-high heat. Lower the heat to medium, and boil, stirring occasionally, until the berries begin to burst, about 5 minutes. Strain through a fine-mesh sieve, pushing down on the berries to extract the juice. Return to the pan and bring to a simmer over medium heat.
• In a small bowl, whisk together the lemon juice and cornstarch. Stir into the blueberry sauce, and cook until it begins to thicken, about 1 minute. 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.
• 把1罐椰奶2夸脱深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 remaining can of coconut milk, the 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 covered and refrigerated for up to 1 week.

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