In a large bowl, place the all-purpose gluten free flour, xanthan gum, Expandex and salt, and whisk to combine.

Create a well in the center of the dry ingredients and add the olive oil, lemon juice and water, and mix to combine.

The dough will come together and be thick.

Press together into a ball, cover with a moist tea towel, and allow to sit for about 20 minutes.

The dough will stiffen a bit as it absorbs more of the water.

Pull off golf ball-sized pieces (about 3 ounces by weight) of the dough, and press into a disk with your fingers.

Place the dough on a clean, flat surface and roll into a rough rectangle about 8-inches long.

Sprinkle lightly with more gluten free flour, and roll into a rectangle about 12-inches x 10-inches.

Using a sharp knife, pizza wheel or pastry cutter, trim the rough edges of the rectangle into a neat rectangle that is about 10-inches x 8-inches.

Dust both sides of the dough generously with more flour, and set aside on a piece of parchment paper.

Gather the scraps and return them to the remaining dough.

Repeat with the rest of the dough, layering the pieces of rolled-out dough on top of one another, each dusted generously with flour to prevent sticking.

The dough can be frozen for later use, then thawed at room temperature before using.

In a heavy-bottom saucepan, heat the olive oil over medium heat.

Add the diced shallot and cook, stirring occasionally, until translucent (about 4 minutes).

Remove the cooked shallots from the pan and set aside.

Add the fresh spinach, and cook, stirring occasionally, until wilted. Remove from the heat and allow to cool.

Once cool, place the spinach in a clean tea towel or strong paper towels and wring out until all water has been removed.

Chop the cooked, dry spinach roughly, and place in the medium-sized bowl with the cooked shallots, feta cheese, egg, salt and pepper, and mix to combine.

Set the filling aside.

Preheat your oven to 350°F. Line a large rimmed baking sheet with unbleached parchment paper and set it aside.

Place 1 sheet of fresh phyllo dough on a lightly floured surface, with the short side of the rectangle facing you.

Sprinkle lightly with more flour, and using a sharp knife, pastry wheel or pizza cutter, cut the rectangle in half lengthwise so you have two equal rectangles, each about 10-inches x 4 inches.

Separate the rectangles and roll each away from you so that it is about 11-inches x 4-inches (or as long as you can make it without the dough tearing). The dough should be nearly translucent.

Brush each rectangle generously with melted butter.

About 1/2-inch from the bottom of each rectangle, place about 1 tablespoon of filling. Pull one of the bottom corners of the rectangle of dough up over the filling on an angle (toward the opposite side of the dough) to make a triangle.

Brush the top of the triangle with more melted butter, and fold it over on itself again toward the other side of the dough rectangle (see photos).

Brush again with melted butter, and continue to fold the dough, brushing with melted butter each time, until you reach the top of the rectangle.

Repeat with the other piece of dough, and then more sheets of phyllo dough and filling.

Place the spanakopita on the prepared baking sheet, about 1-inch apart from one another.

Place the baking sheet in the center of the preheated oven and bake until lightly golden brown all over (about 20 minutes).

Remove from the oven and serve immediately.