Open can of cherries and drain the liquid into a small saucepan. Try to get as much of the liquid out as possible. Whisk granulated sugar and arrowroot into the cherry juice.
Place pan over low heat, stirring constantly until it thickens. This will take 10 minutes or more – be patient, it will thicken even though it seems like it never will.
Remove from heat and continue to whisk for a minute. Gently stir in cherries and Kirsch if using. Allow to cool, and then refrigerate.
To fill a 9″ pie, you will need to double this and use 2 cans of cherries.
This cherry pie filling recipe can be used for the Black Forest Brownie Torte recipe.
I use Oregon brand sour pie cherries in their own juice. They are not sweetened. The 1/2 cup of sugar makes a nice tart topping. Adjust the sugar to taste. If your canned cherries are already sweetened, taste the juice and adjust accordingly. I can sometimes get jars of Zerguit sour cherries which are slightly sweetened and require less sugar.
Use 3 Tbsp of arrowroot for a thicker consistency like a pie. Use 2 Tbsp if you want something more “saucy” as a topping.
This topping will only store in the refrigerator for a couple of days before it starts to separate. You can stir it back together, but it won’t have the quite the same smooth feel as when it’s fresh.