Combine morello cherries, sugar, lemon juice, cinnamon stick, and water in a pot.

Bring the mixture to a boil over medium-high heat.

Once boiling, reduce the heat to low and simmer for 15 minutes to infuse the flavors.

In a separate bowl, whisk together thickened cream, sour cream, and cornflour until smooth.

Pour the cream mixture into the simmering soup through a sieve to avoid lumps.

Cook for an additional 2-3 minutes, or until the soup thickens to your desired consistency.

Remove from heat and let cool.

Refrigerate for at least one hour to chill completely before serving.