To make the filling:

1. Melt the butter in a large skillet over medium heat.
2. Add the garlic and cook for 1 minute, or until fragrant.  
3. Add the spinach, onion powder, salt, pepper, and nutmeg and cook for 2 – 3 minutes, stirring occasionally, unit the spinach is bright green and wilted.  Remove from the heat.
4. Add the feta, ricotta, and mozzarella cheese to the mixture and stir well.  
5. Add the egg and stir until fully combined.  Set aside.

To make the dough:

1. Place the shredded mozzarella cheese and cream cheese in a microwave safe bowl.
2. Microwave, uncovered, on high, for 1 – 2 minutes, or until the cheese is completely melted.
3. Remove from the microwave and stir with a spatula until the cheeses are combined.
4. Add the egg, psyllium husk powder, and almond flour to the cheese mixture.
5. Stir well with the spatula or a fork, until a stiff dough is formed.
6. Knead the dough by hand for 2 – 3 minutes, to ensure all of the ingredients are fully mixed and the dough has a smooth consistency.

To assemble the calzone:

1. Preheat the oven to 400 degrees.  
2. Divide the dough in half.  Press one half out on a parchment-lined cookie sheet into a 12 x 8 rectangle, about 1/4 inch thick.  
3. Spoon the filling onto the center and spread out, leaving a one inch border all the way around.  
4. Turn up the sides and pinch at the corners to hold in the filling (see photo grid in post)
5. On a separate piece of parchment, press out a 13 x 6 rectangle about 1/4 inch thick.  
6. Cut into 3 long strips to braid, or the long strips into 6 shorter strips to lay across.  
7. Braid, or lay the strips crosswise diagonally in a criss cross pattern as desired.  
8. Press the strips into the dough around the edges of the calzone to adhere firmly. 
9. If desired, brush beaten egg yolk over the top of the calzone, and sprinkle with poppy seeds (or sesame seeds) and coarse salt.  
10. Bake for 35 minutes, or until golden brown and slightly puffed.  
11. Remove from the oven and cool for 30 minutes before slicing.