HOW TO MAKE IT :
- Combine the blackberries, . cup granulated sugar and the lemon juice in a medium saucepan and toss well. Let stand until the juices start to pool, about 10 minutes. Mash with a potato masher until the berries are broken down, then cook over low heat until the berries are very soft and the juices are slightly thickened, about 20 minutes.
- Pour the mixture through a fine-mesh strainer into a medium bowl, pressing with a spoon to force out the liquid. Set the liquid aside to cool. Discard the pulp and seeds.
- Heat the half-and-half and remaining 1 cup granulated sugar in a large saucepan over low heat, stirring occasionally, until just simmering. Remove from the heat.
- Beat the egg yolks in a large bowl with a mixer on medium-high speed until pale yellow and thick, 3 to 5 minutes. Temper the egg yolks by slowly drizzling in ¾ cup of the hot half-and-half mixture, whisking constantly. Pour the tempered egg yolk mixture into the saucepan with the rest of the half-and-half mixture, whisking gently as you add it. Simmer over low heat, stirring constantly with a wooden spoon, until very thick, about 5 minutes. The mixture should be thick enough to coat the back of the spoon but not as thick as pudding.
- Pour the mixture through a fine-mesh strainer into a separate large bowl. Add the heavy cream and blackberry syrup; stir to combine. Refrigerate until chilled, at least 4 hours or overnight.
- Churn the mixture in an ice cream maker according to the manufacturer’s directions. When it’s almost ready, make the cheesecake mixture: Beat the cream cheese, lemon zest and powdered sugar in a large bowl with a mixer on low speed until combined, about 1 minute. Increase the speed to medium high and beat until fluffy and very soft, 1 to 2 more minutes.
- Transfer half the ice cream to a freezer-safe baking dish or loaf pan. Spoon half the cheesecake mixture over the top and gently swirl with a butter knife. Repeat with the remaining ice cream and cheesecake mixture. Cover and freeze until firm enough to scoop, at least 8 hours.