Place the cold water in a small bowl and sprinkle over the gelatin powder. Set aside to soften while you prepare the other ingredients.
In a small saucepan over medium heat, bring the cream, honey, vanilla and sugar to a simmer.
Remove from heat, then stir through the softened gelatin.
In a 1 litre jug, whisk the Greek yogurt until smooth.
Pour the hot cream mixture onto the yogurt, whisking to combine.
Pour the mixture into half sphere silicone moulds, small ramekins or glasses (see note)
Leave in the refrigerator overnight to set.
To serve, gently ease the panna cotta from the mould and top with granola and fruit.