In a bowl, mix together all of your dry ingredients.
Cut your butter in rough slices about 1/8 inch thick and add them to the flour mixture. Stir a few times to coat the butter, then add your cold water and stir again just until you get a very rough dough that you can form into a ball. (Alternatively you can use a food processor for this OR simply just grate the butter into the dough, just be careful not to over-mix if doing it this way).
Wrap the rough dough ball and place it in the fridge for 30min to chill.
Next on a coconut/vital wheat gluten floured surface OR between two pieces of greased and very well (coconut/vital wheat gluten)floured parchment paper roll the dough out into a rectangle as best you can (it’s okay if it’s a bit rough the first time, just gently push in the edges if pieces separate – also see my tips on rolling the dough if it’s dry or sticking).
Fold one side of the rectangle inward, then the other until the dough looks like this (see photo).
Push the rough edges in slightly to make the dough neater to work with.
Turn the dough 90* and Roll the dough out into a rectangle again, pushing down the layers you just formed. Repeat this 4-5 times. As you go, the dough will begin to form a nicer looking rectangle and the butter will become streaky and less clumpy.
Fold once more and then wrap your dough and place it in the fridge to cool for another 30min.
While your pastry dough is chilling you can make your filling by mixing together all of the ingredients in a bowl until smooth. Refrigerate until needed.
When your dough has finished chilling, pre-heat your oven to 400*F and then roll your dough out into a large relatively thin but still pliable rectangle (alternatively you can cut the dough into two pieces and make two smaller rectangles if you find that easier to work with).
Next, spread the filling over the whole pastry as best as you can. (I found it helps it stick together better this way). Use your hands to press the filling in place as it may be a bit hard to spread with a spatula.
Roll them up like you would a cinnamon roll. Pinch the long edge together to make sure these don't roll apart in the oven. Then whisk your egg and water together and brush the entire roll with it.
Next cut each log into ~15 pieces using a sharp knife or pizza cutter. Then place them on a parchment lined and greased baking sheet cut-side up.
Brush the cut-side lightly with the egg mixture as well.
Bake the spinach and cheese pastries for 20-25min or until the puff pastry is golden brown and crispy and the cheese is bubbly with small spots of brown. Enjoy your Keto Spinach and Cheese Rolls warm or freeze for later!