Pour milk, cream, sugar, and crème fraiche into a saucepan and whisk until smooth.
Place saucepan over medium-low to medium heat and simmer until sugar dissolves, stirring.
Fill a mixing bowl with ice water and add gelatin sheets to “bloom”. Once sheets have become soft and pliable, stir them into the milk mixture.
Stir until gelatin dissolves.
Remove milk mixture from the stove and pour into 6 4-ounce ramekins. Transfer filled ramekins to a baking sheet and place in the refrigerator to set. Allow panna cottas to set up in the refrigerator for at least 4 to 6 hours and up to 2 days.
Top with berries, pistachios and white chocolate crispy balls, if using. Serve.