Before mixing, drain any excess liquid from the top of the Greek yogurt by pouring off the watery layer.
In a bowl, whisk together the Greek yogurt, cream cheese, and granulated sweetener until smooth and creamy. If using cocoa powder for a chocolate flavor, stir it in until fully combined.
Pour the cheesecake mixture over the oatmeal crust, spreading it evenly.
Cover the cheesecake and refrigerate for at least 4 hours, or ideally overnight, to allow it to set properly.
Once set, slice and enjoy with toppings or as it is.