Preheat the oven to 350°F (175°C). Line an 8-inch or 9-inch square baking pan with parchment paper.

Whisk the almond flour, coconut flour, baking powder, allulose, and salt in a bowl.

Microwave the mozzarella and 2 ounces of cream cheese in 20–30-second intervals, stirring until melted and combined. Alternatively, heat gently in a saucepan over low heat.

Let the cheese mixture cool until warm rather than scorching hot. Beat in the egg and 1 teaspoon vanilla, stirring quickly.

Add the dry ingredients and mix until a pliable dough forms. If the dough is too sticky, chill it briefly; if it stiffens as the cheese cools, warm it gently for a few seconds.

Beat the filling's 4 ounces of cream cheese with 2 tablespoons allulose and the lemon zest until smooth. Add the optional lemon juice if desired.

Roll the dough between two sheets of parchment into an approximately 10-by-12-inch rectangle.

Spread the cream cheese filling over the dough, leaving about ½ inch uncovered along one long edge. Scatter the blueberries evenly over the filling.

Starting from the opposite long edge, roll the dough into a log. Seal the seam gently and refrigerate for about 10 minutes if the log is too soft to slice.

Cut the log into 9 equal pieces and place them cut-side up in the prepared pan.

Bake for 22–28 minutes, checking toward the earlier end of the range. The rolls should be lightly golden and set in the center. Cover loosely with foil if they brown before the centers are ready.

Mix the remaining 2 ounces of cream cheese with 2 tablespoons allulose, the heavy cream, and ¼ teaspoon vanilla until smooth.

Cool the baked rolls for 10–15 minutes, then drizzle or spread the glaze over them. Serve warm or at room temperature.