Place the cookies in a thick, ziplock bag and using a rolling pin, crush them. Set aside.
In a deep skillet, add the cherries, the sugar, a pinch of salt, and grate the ginger over top. Allow to cook into a thick sauce- 10-12 minutes- over medium heat. Remove from heat, and allow to come to room temperature. Transfer to a bowl, and then allow to cool in the fridge.
Heat the milk in a heavy bottom pan. In another bowl, whisk the sugar into the egg yolks, and then add in the flour and corn starch. Whisk to incorporate.
Pour the heated milk into the sugary egg yolk mixture, very slowly, while whisking. Pour the mixture back into the heavy-bottom pan and cook over medium-high heat, whisking constantly. Continue cooking and whisking another 3-5 minutes, until it starts to thicken (lift up the whisk to see if it sticks).
Remove from the heat and stir in the vanilla.
Pass the pastry cream through a mesh colander or screen into a bowl, and allow to come to room temp. Lay a piece of plastic wrap directly on the pastry cream to prevent a skin from forming, and let cool in the fridge.
In small glasses, alternate layers: a dollop of cream, then a dollop of gingered cherry sauce. Right before serving, top with the crushed cookies.