2 sprigs of fresh thyme (plus a few extra sprigs for garnishing later)
2 Tbs muscovado (or dark brown) sugar
1 Tbs water
For the filling
1 cup (225g) mascarpone cheese
2 Tbs cream
1 Tbs honey
For the crust:
Pulse the gingersnaps in a food processor until finely ground into crumbs (you should have about 2 1/2 cups of crumbs). Add the softened butter and pulse a couple times until the dough begins to come together. If you squeeze a clump in your hand and it sticks together, it's ready. Press into a 13 x 4" tart plate and refrigerate for at least 1 hour until solid.
For the plums:
While the crust is refrigerating, halve and pit your plums. In a medium pan, melt the butter. Add the thyme sprigs and the muscovado sugar and stir. Throw in a tablespoon of water and stir for a minute until everything comes together and begins to bubble/caramelize. Add the plums and cook them just for a minute or two per side, until they've begun to soften. Remove from heat and set aside.
For the filling:
Beat the mascarpone in a bowl until it softens up, then add the cream and honey and beat until incorporated and fluffy.
Just before you're ready to serve, remove the tart crust from the fridge and spread with the mascarpone filling. Top with the plums and their juices, and garnish with thyme sprigs.
Best enjoyed the day it's made, but will keep, wrapped in the fridge, for about 3 days.
If you wanted to add a little more thyme flavour, you could always throw 1 tbs of finely-chopped fresh thyme in with the crust ingredients.