Step 1

Place blackberries in a saucepan with sugar,  lemon juice, and salt.

Step 2

Divide the water into two - pour half with the fruit and combine the other half into the cornstarch/cornflour.

Step 3

Heat the fruit on low to medium until sugar is dissolved shaking the pan to cook evenly.

Step 4

Add the well-mixed cornstarch mixture into the bubbling fruit.

Step 5

Continue to cook on low - the mixture will thicken and looks glossy.

Step 6

The color will change from an opaque light red to a deep translucent deep blackberry color (see video)

Step 7

When thick enough to coat the back of a wooden spoon or spatula it's ready.

Step 8

Check consistency - for a cake filling you can make a bit more thicker. Personally, I prefer one consistency for all. Thick not too runny.

Step 9

At this point, you can strain the seeds by simply pouring the filling thru a sieve. Or leave it fruity and chunky just as I have here.

Step 10

Remove from heat - Pour into a mason jar

Step 11

Let cool completely