In a medium saucepan, combine the heavy cream, whole milk, allulose, powdered keto sweetener, and salt. Heat over medium-low, stirring until the sweeteners dissolve completely. Do not boil.

In a separate bowl, whisk the egg yolks until smooth.

Slowly whisk a small amount of the warm cream mixture into the egg yolks to temper them. Continue adding the warm mixture gradually until combined.

Return the tempered mixture to the saucepan and cook over low heat, stirring constantly, until it thickens enough to coat the back of a spoon.

Remove from the heat and whisk in the vanilla extract and xanthan gum until fully incorporated.

Transfer the custard to a bowl and refrigerate for at least 4 hours, or overnight, until thoroughly chilled.

Pour the chilled mixture into an ice cream maker and churn according to the manufacturer's instructions until it reaches a soft-serve consistency.

Fold in any optional mix-ins, such as sugar-free chocolate chunks, chopped nuts, raspberry sauce, or keto caramel, during the last few minutes of churning.

Transfer the ice cream to a freezer-safe container, smooth the top, and freeze for 2–4 hours until firm enough to scoop.

Let the ice cream sit at room temperature for 2–3 minutes before serving for the creamiest texture.