Bake tart shells according to package instructions and set aside to cool (tip: before baking, poke each shell 2-3 times with a fork to keep them from "puffing up" when you bake them!)
While the tart shells are baking, combine rhubarb, water and sugar in a saucepan over medium heat. Bring to a simmer and cook, stirring often, until the rhubarb begins to break down, about 6-8 minutes. Stir in strawberries and vanilla and cook for 5 more minutes, until the strawberries have softened. Transfer mixture to a bowl and refrigerate to cool (at least to room temperature; preferably all the way).
Combine the cream cheese, icing sugar and vanilla in a bowl and beat on low speed until smooth.
In a deep cold bowl whip the whipping cream until stiff peaks form. Add to cream cheese mixture.
Once cooled, add the strawberries and rhubarb.
Spoon mixture into your cooled tart shells.
Chill at least 30m before serving.
Recipe by Feisty Frugal & Fabulous at https://feistyfrugalandfabulous.com/2017/06/strawberry-rhubarb-cream-tarts/