Add blackberries, sugar and lemon juice to a medium saucepan and cook over low heat, covered, for 20 to 25 minutes. Using a fine mesh strainer, drain the mixture by pressing the berries to extract as much liquid and puree as possible. Set aside.

In medium saucepan over medium heat, heat half-and-half until very hot but not boiling, remove from heat and set aside.

Place egg yolks, vanilla bean seed and sugar in the KitchenAid Stand Mixer bowl fitted with the wire whip attachment. Turn to Speed 2 and mix for about 30 seconds, until well blended.

With the mixer still on Speed 2, gradually add the half-and-half and mix until blended. Return the mixture to a medium saucepan and cook over medium heat, stirring constantly, until small bubbles start to form around the edges. Remove from heat and transfer to a large bowl.

Stir in whipping cream. Add the blackberry mixture to the custard, stir it in until well combined, then cover and chill for at least 8 hours.

Attach the cooled KitchenAid Ice Cream Maker. Turn the mixer to STIR (Speed 1). Pour the ice cream mixture into the bowl slowly. Continue running the mixer on STIR (Speed 1) for 15 to 20 minutes or until desired consistency is reached. Immediately transfer ice cream into an airtight container, using a spatula mix in chocolate chips, cover and freeze for 2 hours before serving.