In a food processor fitted with a metal blade, pulse the powdered sugar and flour until combined. Add 1 cup of the butter, 1 cube at a time, pulsing to combine. Add the cream and pulse until the mixture forms into a ball. Turn the dough onto a sheet of plastic wrap and cover tightly, pressing the dough into a thick disk. Refrigerate for 1 hour. 

Preheat oven to 325F. 

On a clean, floured surface, roll the dough out and carefully transfer to  a pie dish or tart pan. Prick the crust all over with a fork, then parbake for 10 minutes. Remove from the oven and set aside to cool. Increase the oven temperature to 350F.

In a small bowl, stir together the cornstarch and water. Set aside.

Combine the cherries, remaining 1 tablespoon of butter and vanilla in a saucepan. Cook, stirring occasionally, for 10 minutes, until the cherries begin to release their juices, about 10 minutes. Stir the cornstarch slurry into the cherry mixture, and continue to cook until the cherry mixture coats the back of a spoon. Remove from heat and allow to cool.

While the cherry filling cools, make small, 1/2-inch balls of the almond paste and arrange on a cutting board or plate.

Pour the cooled cherry filling into the par-baked tart shell. Top the cherries with the almond paste balls, and bake for 20 minutes. Remove from oven and let cool for at least 30 minutes before serving.