1. Preheat your oven to 350 F (175 C). In a medium bowl, combine the almond flour, half of the erythritol (¼ cup), and melted butter. Mix until well combined and crumbly. Press this mixture firmly into the bottom of an 8×8-inch baking pan lined with parchment paper, leaving an overhang on two sides for easy removal. Bake the crust for 10-12 minutes, or until lightly golden. Remove from the oven and let it cool slightly while you prepare the filling.

2. In a large mixing bowl, using an electric mixer, beat the softened cream cheese until smooth and creamy, about 1-2 minutes. Make sure there are no lumps.

3. Add the remaining erythritol (¼ cup), eggs, heavy cream, lemon juice, lemon zest, and vanilla extract to the cream cheese mixture. Beat on medium speed until all ingredients are thoroughly combined and the mixture is smooth and uniform. Scrape down the sides of the bowl as needed.

4. Gently fold in the fresh blueberries into the cream cheese mixture. Be careful not to overmix, as this can crush the berries.

5. Pour the cream cheese and blueberry filling evenly over the partially baked crust in the prepared pan.

6. Return the pan to the oven and bake for 25-30 minutes, or until the edges are set and the center is only slightly jiggly. The top should be lightly golden.

7. Remove the pan from the oven and let the bars cool completely on a wire rack at room temperature. Once cool, transfer the pan to the refrigerator and chill for at least 2 hours, or preferably longer, to allow the bars to fully set.

8. Once thoroughly chilled, use the parchment paper overhang to lift the bars out of the pan. Slice into 9 or 16 squares, depending on your desired serving size.