Preheat the oven to 350°F. Line a muffin pan with 9 cupcake liners.
Place the oats and nuts in the bowl of a food processor; pulse until the oats and nuts are coarsely chopped. Transfer the mixture to a bowl and stir in the cinnamon, coconut oil, and sweetener.
Spoon a heaping tablespoon of the oatmeal mixture into each of the cupcake liners, pressing the mixture down with a spoon. Bake for 10 minutes then remove from oven and cool completely.
Using a mixer, beat the cream cheese until smooth. Add the Greek yogurt, sweetener, egg, and vanilla. Beat until completely smooth.
Divide the filling evenly between the muffin liners.
Bake in the oven for 25 minutes, until centers are set.
Allow to cool completely, then place in the refrigerator to chill.
When you're ready to serve the cheesecakes, remove the paper liners and top them with the berries and mint sprigs (optional).
Store any remaining cheesecakes in the refrigerator.