Line and lightly grease a cake tin that fits in your air fryer.
Whisk Greek yogurt and eggs together until smooth.
Add sweetener and vanilla, whisking until fully combined.
Sift in tapioca flour or cornstarch and mix until the batter is smooth.
Pour the batter into the prepared pan and smooth the top.
Scatter blueberries evenly over the surface.
Air fry at 150°C / 300°F for 60–65 minutes until mostly set with a slight wobble.
Remove from the air fryer and cool completely in the pan.
Carefully remove from the tin and slice.
Serve plain or with extra blueberries.