Blackberry and Damson Tart

In separate pans, cook the damsons and blackberries with enough water to cover them

Drain and reserve the liquid

Remove the pits from the blackberries and cut the fruit into small pieces

In a small pan, mix together the sugar and cornstarch

Add the reserved liquid and add water if necessary to obtain 1 cup of liquid

Add this mixture to the pan

Add the lemon juice

Cook over medium heat, stirring constantly, until the mixture thickens and comes to a boil

Let it simmer for 1 minute, stirring constantly

Add the fruit pieces

Check the taste and add more sugar if desired

Let it cool down

Place the filling into the cooked tart crust

If desired, serve with whipped cream.