For the panna cotta, lightly grease 8 half-cup ramekins or serving dishes.
Place 1/2 cup heavy cream into a medium saucepan, sprinkle gelatin overand let sit for 3 minutes.
Add remaining cream, instant coffee and granulated erythritol, and set over medium heat, whisking until gelatin, coffee and erythritol are dissolved. Cook until mixture begins to steam but does not boil.
Remove from heat and stir in Greek yogurt, vanilla and stevia until smooth.
Divide between prepared ramekins, wrap in plastic wrap and chill at least 3 hours.
For the raspberry coulis, process raspberries and powdered erythritol in a food processor until pureed.
Set a fine-mesh sieve over a bowl and drain, pressing on solids to get as much liquid through the sieve as possible. Stir in lemon juice.
If you want to unmold your panna cotta, sit the ramekin in several inches of hot water, then run a sharp knife around the outside and invert onto a plate. Alternatively, you can leave it in the serving dish. Drizzle with raspberry coulis and serve.
Serves 8. Each serving has 6.5 g of carbs and 2 g of fiber. Total NET CARBS = 4.5 g.