To make the sauce, add the blackberries, water and sweetener to a small saucepan. Bring to a boil then simmer for 10 minutes. The fruit will break down and the liquid will reduce. Sprinkle over a little xanthan gum if a thicker sauce is required. The sauce can be made in advance.
Preheat the oven to 350F.
Make the dough by placing the mozzarella and cream cheese in a medium size microwaveable bowl. Microwave for 1 minute, stir and then cook for another 30 seconds. Stir in the almond flour and most of a the beaten egg (reserve a little for brushing over the top).
Let the dough cool slightly, then place it on a silicone mat. Cover it with another mat and use a rolling pin to flatten it into a circle.
Remove the packaging from the brie and place it in the center of the dough. Fold up the edges of the dough, pinching the seams together and leaving a hole at the top.
Brush the top with the reserved egg, then lift up the silicone mat and transfer it to a baking pan.
Bake for 20 minutes, then carefully transfer the cooked brie to a serving platter, and add the sauce to the top. Serve immediately.
3g net carbs per serving (a quarter of the brie with sauce)