Where is this wonderful recipe for blackberry filling! I'm about to destroy my keyboard with drool! 
My mom gave us some homemade blackberry jam a few months back and now I am eager to find something equally delicious to feed my blackberry love!
I could tell you, but I'd have to kill you

Nah, it's actually quite easy, here it is.
Blackberry Filling2 16 ounce packages of frozen blackberries (not packed in syrup)
1 1/3 cups water
1 1/2-2 cups granulated sugar (or to taste. 2 cups will be pretty sweet)
5-6 T of cornstarch dissolved in 1/2 cup of water
In a saucepan combine the blackberries, water, and sugar. Bring to boil and simmer for 15-20 minutes or until the blackberries have broken down. Remove the mixture from the heat and strain with a fine mesh sieve to mash the blackberries. Combine the liquid and the solids in the strainer and return mixture to the heat. Dissolve the cornstarch in 1/2 cup of water. Whisk the slurry into the blackberry mixture. Bring the mixture back to a boil and simmer for 5 more minutes, stirring occasionally. Remove from heat and cool completely.
It is not my recipe and the original one called for ony the juices after straining be used but I used everything. It made it thicker and you cannot feel the seeds in the cake. It was delicious.
June