Step 1: In a medium bowl, whisk together the cold whole milk, granulated sugar, and salt until the sugar is completely dissolved. Set aside.
Step 2: In a separate large, very cold bowl (chilled in the freezer for 10-15 minutes), whip the very cold heavy cream with an electric mixer on medium-high speed until stiff peaks form. Be careful not to overbeat, or it may turn grainy.
Step 3: Gently fold the milk and sugar mixture into the whipped cream using a spatula. Add the vanilla extract (or vanilla bean seeds) and continue to fold until just combined, ensuring not to deflate the whipped cream. Overmixing will reduce the creaminess.
Step 4: Pour the ice cream mixture into a freezer-safe container (a loaf pan, an airtight container, or a shallow metal pan works well). Cover tightly with plastic wrap, pressing it directly onto the surface of the ice cream to prevent ice crystals.
Step 5: Freeze for at least 6-8 hours, or preferably overnight, until firm. For best results, remove from the freezer 5-10 minutes before serving to allow it to soften slightly for easy scooping.