If Cooking Sous Vide: Preheat a sous vide circulator to 180°F (82°C). In a medium bowl, whisk together cream and baking soda (if using). Place zipper-lock bags or vacuum bags in a tall pitcher or jar to stand them upright, then pour cream into bags. Remove air from zipper-lock bags using the water displacement method , or use a vacuum sealer to seal vacuum bags. Cook for 24 hours. Remove bags of cream and chill in the refrigerator before using.

If Cooking in a Pressure Cooker: In a medium bowl, whisk together cream and baking soda (if using). Divide cream between two 12-ounce Mason jars and screw on tops until just finger-tight. (If the tops are screwed on too tightly, they may break during cooking.) Insert steamer rack into pressure cooker and add 1 inch water. Place jars in pressure cooker, close, and bring to full pressure. Cook at full pressure for 2 hours. Remove cooker from heat and allow to depressurize naturally. Cool cream before using.