Step 1

Using a food processor or blender, puree the blackberries.

Step 2

Press the puree, using the back of a large spoon, through a fine-mesh strainer set over a medium saucepan. Get rid of the seeds.

Step 3

Add the lemon juice and granulated sugar to the puree. Over medium heat, bring the mixture to a boil. Reduce the heat to medium-low. Simmer while stirring frequently for about 10 minutes or until thickened.

Step 4

Remove from heat and allow to cool. Put in the fridge if needed.

Step 5

In a medium bowl, combine the cream, powdered sugar, and vanilla.

Step 6

Beat on low using an electric mixer until it starts to thicken, and increase the speed to medium and then high. Beat until stiff, firm peaks form.

Step 7

Spoon 3/4 of the puree into the whipped cream. Fold 3 or 4 turns. This should make thick streaks of the blackberry puree remain visible.

Step 8

Divide the Blackberry Fool mixture between 6 decorative glasses.

Step 9

Drizzle with the remaining puree.

Step 10

Top with fresh blackberries and a sprig of mint if desired.