Warm the dairy base. In a medium saucepan, whisk together the heavy cream and almond milk.
Heat over medium until steaming but not boiling.
Whisk the yolks and sweetener. In a separate bowl, whisk the egg yolks with the erythritol/monk fruit blend until lighter in color. This helps them incorporate smoothly.
Temper the eggs. Slowly ladle about 1/2 cup of the hot cream into the yolk mixture, whisking constantly. Repeat with another 1/2 cup.
Then pour the tempered yolks back into the pot, whisking as you go.
Cook into a custard. Stir the mixture over medium-low heat for 4–6 minutes, until it thickens slightly and coats the back of a spoon. Do not boil. Remove from heat.
Blend in pumpkin and flavorings. Whisk in pumpkin puree, cream cheese, vanilla, pumpkin pie spice, extra cinnamon, salt, and allulose (if using).
Blend with an immersion blender for ultra-smooth texture, or whisk vigorously until silky.
Chill completely. Pour into a shallow container, press plastic wrap onto the surface, and chill in the fridge for at least 4 hours, or overnight. Cold base = better texture.
Churn or no-churn. With ice cream maker: Add vodka (if using), churn per machine instructions until thick and soft-serve like, 20–25 minutes.
No-churn: Add vodka (if using), pour into a loaf pan, and freeze. Stir vigorously every 30–45 minutes for 2–3 hours to break up ice crystals, then freeze until firm.
Fold in “crust.” If using pecans, almond crumble, or keto cookie bits, gently fold them in at the end of churning or after the final stir in the no-churn method.
Freeze to set. Transfer to a lidded container and freeze 2–4 hours for scoopable firmness.
If frozen solid, let it sit at room temp 10–15 minutes before serving.