5 1/2 ounces plain or Toasted Sugar (about 3/4 cup; 145g)
4 ounces egg yolk (about 1/2 cup; 110g), from about 8 large eggs
3/4 teaspoon (3g) Diamond Crystal kosher salt, plus more as needed; for table salt, use half as much by volume or use the same weight
6 3/4 ounces Oreo wafer crumbs (about 1 1/2 cups; 190g), from store-bought or homemade cookies
11 ounces whole milk (about 1 1/4 cups plus 2 tablespoons; 310g)
9 ounces heavy cream (about 1 cup plus 2 tablespoons; 255g)
1/4 ounce vanilla extract (about 1/2 tablespoon; 7g)
3 ounces roughly chopped Oreo sandwich cookies (about 1/2 cup; 85g), from store-bought or homemade cookies (optional)
1. Combine sugar, egg yolks, and salt in a 3-quart stainless steel saucier, then whisk in cookie crumbs, milk, and cream. Cook over medium-low heat for a few minutes, until warm to the touch. Increase heat to medium and cook, stirring and scraping constantly with a flexible spatula, until you can see steam rising from the custard and it registers 155°F (68°C) on an instant-read thermometer, about 8 minutes. Pour through a fine-mesh sieve into a large stainless steel bowl, pressing gently with a flexible spatula to release the liquid trapped in the crumbs, then stir in the vanilla.
2. Fill a sink compartment or extra-large bowl with a few inches of ice water and place bowl with custard inside, stirring from time to time, until cool, about 30 minutes. Cover and refrigerate until no warmer than 40°F (4°C), about 4 hours. (The ice cream base can be kept refrigerated for up to 1 week.) Churn in an ice cream machine according to the manufacturer’s directions. Meanwhile, place a 1-quart container and flexible spatula in the freezer.
3. When ice cream looks thick and light, shut off the machine; if desired, fold in crushed cookies with the chilled spatula, then transfer ice cream to the chilled container. Enjoy as soft-serve, or cover with plastic pressed directly against surface of ice cream, then close lid and freeze until hard, about 4 hours.