World class? Well, better than shop-bought.

Get:

1 Cuisinart ice cream/sorbet maker, the type with a hollow-walled
container that you keep in the freezer, or similar device.

Ingredients:

1 lb packet frozen blackberries
12 oz can of evaporated milk
11.5 oz can of guava nectar (an extremely sweet type of canned fruit
juice that Hispanics love).

1. Liquidize frozen blackberries in food processor (skip this step if
you like).

2. Put all ingredients in ice cream maker and turn on.

3. If you skipped step 1 poke the mixture a bit with a spoon as it
rotates to crush the blackberries.

4. Whirl it about 5 minutes and serve, or decant into container and
store in freezer.

Goes great with apple pie.

This should also work with other berries, though you will need to
implement step 1 with strawberries.