In the bowl of a food processor fitted with the steel blade (See Recipe Notes), place the flour, xanthan gum, Expandex (or tapioca starch), salt, olive oil, eggs and egg yolks, and pulse until combined.
Add 1/3 cup water to the mixture in the food processor, and process until the dough is moistened.
Turn on the food processor on low speed, remove the hopper and add more water very slowly until the dough clumps to one side of the food processor.
Transfer the dough to a lightly floured surface and divide it into 4 parts. Work with one part at a time and cover the others with plastic wrap to prevent the remaining pieces from losing moisture.
Working with one piece at a time, with clean hands, knead the dough until smooth and roll into a rectangle.
Roll each piece of dough into a rectangle about 8-inches wide by about 10 inches long, trimming rough edges with a sharp knife or pastry or pizza cutter.
Slice each rectangle into 3 strips, each about 2 1/2 inches wide by 10-inches long.
Repeat the process with the other 3 pieces of dough, for a total of 4 pieces, each cut into 3 strips. You should have 12 strips of pasta.
Stack and cover them with a damp towel or plastic wrap and set it aside.
Prepare the filling.
In a large bowl, place the egg, salt and pepper, and whisk to combine well. Add the ricotta, spinach, mozzarella cheese and about half of the Parmigiano-Reggiano cheese, and mix to combine.
Fill the raw ravioli.
On a flat surface, place 6 strips of the pasta side by side.
Place dollops of about 1 tablespoonful of the filling, about 2 inches apart, along the length of the pasta.
With wet fingers, moisten the perimeter of each piece of pasta dough, and moisten between each dollop of filling.
Place one of the remaining 6 strips of pasta dough over one of the filled pieces, and press down to seal everywhere you moistened (along the perimeter and between each dollop of filling), eliminating any air bubbles.
Repeat with the remaining pieces of dough.
Using a sharp knife or fluted pastry cutter, trim along the perimeter and between each dollop of filling to create square, filled raviolis.
Allow the pasta to dry.
Transfer the raviolis to a flat surface sprinkled lightly with gluten free flour and allow to dry for about 10 minutes.
Boil the ravioli.
While the ravioli are drying, bring a large pot of salted water to a rolling boil.
Place the ravioli in the water in batches, taking care not to crowd the water.
Boil for about 8 minutes or until the ravioli have begun to swell in size and the dough is fork tender and the filling is cooked.
Remove from the water with a slotted spoon or strainer and serve immediately with the tomato sauce and remaining Parmigiano-Reggiano cheese.
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Notes
About Expandex modified tapioca starch.For information on where to find Expandex, please see the Resources page.For information on how to replace Expandex with Ultratex 3, readily available in most countries outside the United States, in the gluten free bread recipes in GFOAS Bakes Bread, scroll to #6 in ResourcesI have not yet tested Ultratex 3 in this recipe, but I would recommend trying 15 grams Ultratex 3 in place of Expandex, and adding another 30 grams of Better Batter to the recipe. Ultratex 3 is at least 3 times as strong as Expandex.Although Expandex is a modified tapioca starch and is not equivalent to regular tapioca starch, in this recipe they can be used interchangeably. You will likely need more additional water in your homemade pasta if you are using Expandex, and less if you are using tapioca starch.About making the pasta in a food processor.If you don't have a food processor and need instructions on how to make this fresh gluten free pasta dough without one, please click through to the dedicated post on how to make gluten free pasta.