Source: The Martha Stewart Show, January Winter 2009
Prepare an ice-water bath and set a medium bowl over it. Place gelatin in a bowl filled with enough cold water to completely cover; let soften.
In a small saucepan, heat sugar and 1 cup plus 3 tablespoons heavy cream over medium heat, stirring, until sugar is dissolved. Strain gelatin through a fine mesh sieve. Add gelatin to sugar mixture, along with remaining 1 3/4 cups heavy cream; stir to combine.
Strain into bowl set over ice-water bath to cool. Transfer mixture to a 1-quart container and refrigerate panna cotta until set.
Place two tablespoons panna cotta in each of 10 bowls. Garnish with sorbet and gelee cubes. Pour 2 tablespoons prosecco into each bowl and serve immediately.