Instructions:

Blackberry Pie Filling

6 quarts fresh blackberries
7 cups granulated sugar (can make slight
    adjustments for tartness of berries)
1 3/4 cups Clear Jel
1 teaspoon cinnamon
9 1/3 cups water
1/2 cup bottled lemon juice (this is for
    safety, do not decrease amount)

Select top quality, firm, ripe berries. Rinse berries and set aside.

Measure lemon juice and set aside.

Combine Clear Jel, sugar and cinnamon in a large saucepan. Add water and mix until smooth. Stirring during the thickening process is critical for a smooth end product. Heat, stirring mixture constantly until it bubbles. Quickly add lemon juice and boil 1 minute, stirring constantly. (you may add more water at this point if you wish to have a berry topping instead of pie filling). Remove from heat and fold in berries.

Fill 7 quart jars, leaving 1 to 1 1/2 inches of headspace. Process in a boiling water canner for 30 minutes at sea level, 35 minutes at 1001 to 3000 feet and 40 minutes at altitudes 3001 to 6000 feet. Each quart of pie filling will make an 8- or 9-inch pie.

Let me know if you try this and how it turns out. I plan to pick my blackberries this weekend.

I used tapioca instead of Clear Jel. It turned out just fine.