I've got a major thing for fruity, Philadelphia-style ice cream—a straightforward combination of fruit, cream, and sugar. Normally, I'm all about roasting watery fruits like strawberries and cherries, a relatively gentle cooking method that concentrates their juices in the oven.
But when the thermostat starts to climb, it's worth working with direct heat on the stovetop if that means keeping the oven off and the kitchen cool. Especially when it comes to blackberry ice cream, where the fruity base can benefit from the deeper, jammy flavors cultivated by direct heat.
The process is a straightforward one: combine fresh blackberries and sugar in a 3-quart stainless steel saucier, then smash with a metal spatula to break up the berries and release their juice (compared to the dull edge of a potato masher, I find the spatula's sharp edge greatly reduces the risk of splashing).
Once the berries are swimming in juice, bring the mixture to a simmer over medium heat and cook until reduced by 14 ounces—a process that's dead easy to monitor with a digital scale (in fact, without one, the mess and margin of error are high enough for the recipe to lose its allure altogether).
This reduction drives off about 35% of the fruit's water content, concentrating the blackberry flavor and eliminating potential fuel for iciness in the finished product; if done inaccurately (as is inherently the case with volume measurement), the results have the potential to be both bland and icy, which makes a digital scale absolutely essential.
After the reduction, I strain the mixture to extract the concentrated blackberry purée and remove the bitter seeds. In the end, I discard about 10 ounces of seedy pulp, leaving me with about 20 ounces of concentrated, lightly sweetened blackberry purée. This is cut with a splash of fresh cream, giving the base all the structure it needs to churn up thick and light down the road.
If the berries are particularly sweet and mild, the base can be doctored with a splash of lemon juice to cut through the cream's richness and a pinch of cinnamon to amp up their aroma (the latter I'd recommend even with top-notch berries, as cinnamon has a way of helping blackberries really pop). A few teaspoons of bourbon can help with the ice cream's aroma as well.
However the base is adjusted, it needs to be refrigerated until thick and cold, no warmer than 40°F (4°C). This can be done rather quickly in an ice bath, or passively in the fridge, before churning in an ice cream maker.
Let the ice cream churn until fluffy and thick, but not necessarily the color you see here. The exact appearance of the ice cream will vary depending on the berries themselves, which can produce colors ranging from bright fuchsia to deep burgundy. Likewise, the specific flavor of the ice cream can vary wildly depending on the quality of the fruit.
Transfer to a 4-cup capacity non-reactive, freezer-safe container (whether that's a specialty container, an empty yogurt bin, or an anodized aluminum loaf pan), and freeze until firm enough to scoop.
However it's served, this ice cream celebrates summer blackberries at their peak, so seek out the best you can find.