Pour 1 cup of milk into a medium saucepan and add the sugar and salt. Warm over medium heat, stirring, until the sugar is dissolved. (Do not let it get to a boil.)

Remove from the heat and add 2 1/4 cups of heavy whipping cream. Stir in the vanilla extract.

Chill the mixture thoroughly in the refrigerator, for about 4-12 hours.

In a small saucepan, combine the raspberries, ¼ cup sugar, lemon juice, and cornstarch. Mash the raspberries with a fork, and stir over medium heat for about 5 minutes, until it looks a little thicker, like a jelly.

Pour the sauce through a fine mesh strainer into a bowl, pressing through with a spoon to extract as much of the juice from the raspberries as possible. Discard the seeds and cool the sauce down in the fridge for about an hour, or longer.

When ready to churn, freeze the mixture in your ice cream maker according to the manufacturer's instructions, for about 25-30 minutes. It will be like a soft serve consistency. Put 1/2 of it in a container and then drizzle on half of the raspberry sauce, then repeat the layers. Use a knife to swirl the layers in a figure 8 motion. Freeze until the ice cream reaches desired consistency.