Process the raspberries in a blender until they form a smooth puree, then push the mixture through a fine-mesh strainer into a bowl. Use a spatula to press gently and extract all the puree while keeping the seeds in the strainer. Set the strained puree aside at room temperature while you make the custard base.

Place the egg yolks, sugar, salt, and heavy cream in a heavy-bottomed pot. Cook over medium heat, whisking or stirring constantly with a wooden spoon, until an instant-read thermometer reads 165°F. The custard should appear slightly thickened and coat the back of your spoon. Using a pot with a light-colored interior helps you watch the custard's color as it cooks.

Transfer the hot custard to a clean bowl. Stir in the vanilla extract gently, then fold in the raspberry puree from the first step until everything is well combined and the mixture turns a lovely pink shade. Cover the bowl and place in the refrigerator for a minimum of 6-8 hours, or until the custard is thoroughly chilled to 40°F or lower. Chilling overnight produces the best final texture and allows the flavors to develop fully.

Transfer the chilled custard to your ice cream machine and process following the manufacturer's directions, usually 20-25 minutes, until it reaches a soft-serve texture. Move the churned ice cream into a freezer-safe container and freeze for at least 4-6 hours until it becomes firm enough to scoop properly. The churning process adds air and creates the smooth, creamy consistency that distinguishes homemade ice cream from commercial varieties.