Step 1

Prepare an ice bath by combining cold water and ice cubes in a small mixing bowl. Lightly grease a dinner plate with butter or ghee. If using silicone molds, grease them lightly with butter or ghee; if you are not using silicone molds, lightly grease a rimmed baking sheet with butter or ghee.

Step 2

Combine sweetened condensed milk and ground cashews in a 3-quart saucier and stir with a rubber spatula until smooth. Place over low heat and, stirring constantly, bring mixture to 179°F (81°C), taking care not to exceed 180°F (82°C). Continue stirring constantly to prevent scorching or caramelization and cook until mixture reduces to a very thick paste the consistency of very thick, creamy peanut butter, 15 to 45 minutes. (Timing will depend on how closely you maintain a cooking temperature of 179°F.)

Step 3

To Test the Dough: Using a 1-teaspoon measuring spoon, drop a walnut-size portion of dough into the prepared ice bath and wait 1 minute. Using clean fingers, remove the chilled dough and try to form it into a ball; if the dough easily forms a non-sticky ball, the dough is ready. If the dough does not easily form a ball or is still quite sticky, continue to heat the cashew mixture over low heat, stirring constantly, and keep testing dough every 2 minutes until it reaches the desired consistency.

Step 4

Remove dough from heat and add 1 tablespoon (14g) butter or ghee and vanilla extract, stirring to thoroughly combine. Transfer dough to prepared, lightly greased plate and spread it out into a flat, even layer. Set aside and let cool to room temperature, about 2 hours.

Step 5

Grease your palms and fingers with 1 teaspoon (5g) of butter or ghee and knead cooled dough until it is no longer sticky, about 4 minutes.

Step 6

If Using Silicone Molds: Portion dough into molds and, using knife, trim dough so it is flattened flush with the top of the mold. Set molds on the counter, covered with a clean kitchen towel if desired, until the surface is firm to touch and slightly dry, about 12 hours. Unmold milk creams and serve.

Step 7

If Using Rimmed Baking Sheet: Working with 1 tablespoon (20g) of dough at a time, shape dough into 1-inch discs and transfer them to the prepared baking sheet, leaving a 1-inch (2.5cm) space between each milk cream. Using a fork, prick the tops of the milk cream discs to form a decorative pattern. Set the baking sheet on the counter, covered with a clean kitchen towel if desired, until the surface is firm to touch and slightly dry, about 12 hours. Serve.