In a pot with a heavy bottom, bring Saskatoons and waters to a boil. Simmer for 5 minutes. Mix together the cornstarch and sugar and slowly add to the fruit, stirring constantly, until the mixture is thickened. Remove from heat, add lemon juice and almond extract and let cool. In view of the altitude here, we have to bake cakes and pastry a bit longer than at sea level. As a result, after baking for 90 minutes, I spread a layer of Saskatoon berry sauce over the top of the nearly done cake, and returned it to the oven for another 20 minutes.