Place a medium bowl (preferably metal) in the freezer to chill. (If space is limited, place in the refrigerator.)
Wash, dry, and zest the orange into another medium bowl.
Juice the orange into a medium saucepan. Add cherries and sugar to the pan, stir to combine, and set aside to thaw.
2 cup frozen cherries
¼ cup granulated sugar
Meanwhile, using a box grater, coarsely grate cream cheese into the bowl with the orange zest; add vanilla and cardamom. Use a silicone spatula or fork to soften and combine the cream cheese mixture, creating a smooth cream.
⅔ (8 oz) block cream cheese
1 tsp vanilla extract
⅛ tsp cardamom, ground
Using a strainer, sift powdered sugar into the bowl with the cream cheese. Use the spatula or fork to mash and combine the mixture until smooth and no lumps remain. Set aside.
⅔ cup powdered sugar
Remove bowl from the freezer. Pour cold cream into the bowl; use a whisk (or hand blender) to beat the cream vigorously, until medium-soft peaks form, about 3 minutes if whisking. (When you pull the whisk out of the bowl, the cream should hold its shape, with a peak that curls over slightly.)
8 fl oz (1 cup) heavy cream
Transfer half of the whipped cream to the bowl with the cream cheese mixture. Using a silicone spatula, gently fold the two together until almost combined. Add remaining whipped cream and continue to fold until just combined.
Divide the mousse between small bowls, cups, or jars. Cover with plastic wrap or lids and refrigerate until set, about 1 hour (or overnight).
While the mousse sets, make the cherry compote. Place the saucepan with the cherry mixture over medium heat and bring to a simmer.
In a small bowl, make a slurry by whisking water with cornstarch until smooth.
¼ cup water
4 tsp cornstarch
When the liquid in the saucepan is simmering, add slurry in a steady stream while stirring quickly with a silicone spatula. Simmer until sauce thickens, about 2 minutes. Remove from heat.
Transfer cherry compote to a small, heat-proof bowl or container and let cool to room temperature. Cover with plastic wrap or a lid and refrigerate until ready to use.
Right before serving, roughly chop pistachios.
¼ cup pistachios, unsalted
To serve, top mousse with cherry compote and pistachios. Enjoy!