Preheat the oven to 180C / 350F electric or 160C / 320F fan assisted. Line a baking sheet with parchment paper.
Melt the mozzarella and cream cheese in a microwave for around 1 minute. Or, heat in a non-stick saucepan over a low heat. The cheese should be melted, but not bubbling.
In a separate bowl, combine the dry ingredients: almond flour, coconut flour, baking powder, powdered sweetener and dry active yeast, if using.
Add the dry to the wet ingredients and add the egg. Start to combine using a fork, then use your hands to make a ball of smooth dough.
Roll out the dough into a rectangle between two sheets of parchment paper, about ¼ inch or 5 mm thick. Fold over the edges of the parchment to create a straight line. Lift the top parchment.
Cut into 3 rectangles, then cut into 6 long triangles.
Re-roll each triangle so it is evenly shaped and around 19 centimetres long. Again, I like to fold the edges of the parchment paper to shape the dough. Then, roll up into a crescent shape. Place on a baking sheet lined with parchment paper. Option to brush with melted butter.
Bake in the oven for 20 minutes or until golden and puffed. Once the croissants are golden brown (after 13-14 minutes), loosely place aluminium paper over them for the remainder of the oven time. This prevents them from over-browning.