The more milk fat in the milk you choose will result in creamier more luxurious texture to the final product, but even with skim milk you will end up with a nice frozen treat.

Whisk together sugar, cornstarch, & salt to mix. Add milk & cream, whisk well with other ingredients. Warm over medium heat stirring constantly for 10 to 15 minutes or until it thickens slightly. Remove from heat.

In a mixing bowl whisk the egg yolk. Gradually whisk 1 cup of the hot cream mixture into the yolk. Add remaining milk mixture while whisking constantly. Stir in vanilla. Alow to chill for about an hour covered & stirring occasionally to prevent a skin.

Meanwhile, cook the blackberries in a saucepan on medium low heat with the sugar & cornstarch until they are warmed through & the liquid created thickens a bit. Stir regularly & mash the berries up a bit while doing so. Remove from heat & cool.

Stir the two mixtures together. Place in your ice cream maker & follow the manufacturer's instructions. Freeze for two hours. Set ice cream out for 15 minutes before serving.