In a large bowl, whisk together sweetened condensed milk, heavy whipping cream, and half and half.
14 ounce can of sweetened condensed milk, 1/2 cup heavy whipping cream, 2 1/2 cups half and half
Whisk in the vanilla and 2 tablespoons of the blackberry jam. Chill in the refrigerator for 2 hours.
1 Tablespoon vanilla extract
Pour the mixture into your ice cream maker and process according to the manufacturer’s instructions (usually 20-30 minutes).
Meanwhile, while the ice cream is churning, whisk the remaining blackberry jam to break up any chunks. If need be, you can soften it slightly in the microwave, but be sure it’s cool before the next step.
Scrape ice cream into a square or loaf pan. Place dollops of the remaining blackberry jam on top and gently swirl it in with a butter knife or icing spatula.
*It’s best to chill the liquid ingredients before adding them to the ice cream maker, as it helps the process. The sweetened condensed milk is at room temperature and will bring the temperature of the other chilled ingredients up. Cold ingredients allow the machine to freeze faster, which means smaller ice crystals. Smaller ice crystals produce creamy ice cream! Do not skip the step that calls for chilling the ice cream base in the fridge for 2 hours.*
You need some fat for ice cream, but if you’re concerned about the calories and fat from heavy whipping cream and half and half, you can replace 1 1/2 cups of the half and half with milk.