Combine milk, 1/4 cup sugar, salt, and vanilla in a medium saucepan and cook over medium heat until just starting to bubble around the edges, about 3 minutes.

Meanwhile, whisk together egg yolks and remaining 1/4 cup sugar in a medium bowl until thick and pale yellow. Add 1/3 of the hot milk mixture to the egg mixture, whisking until combined. Pour egg mixture into rest of hot milk mixture and continue to cook over medium heat, stirring constantly with a wooden spoon, until mixture is thick enough to coat the back of a spoon, about 5 minutes.

Strain liquid through a fine wire mesh strainer into a medium bowl set over another large bowl of ice water. When liquid is strained, stir until cooled to room temperature, about 5 to 7 minutes. Pour base into an ice cream maker and process according to manufacturer’s instructions. When ice cream has reached soft serve consistency, transfer to an 8x4-inch loaf pan. Cover and freeze until firm, at least 4 hours or up to 1 week.

For cookies and cream variation: when ice cream has reached soft serve consistency, stir in chopped Oreos. Transfer base to an 8x4-inch loaf pan, cover, then freeze until firm, at least 4 hours or up to 1 week.