6 cups spinach, lightly packed
3 cups all purpose flour
3 tablespoons unsalted butter
1 1/2 teaspoons salt
2 to 3 tbsps. water, plus more as necessary
Place spinach in microwavable bowl and microwave on high for 1 minute. Set aside.
Add the flour, salt, and butter to a food processor and pulse until combined. Add the spinach and process until fully combined with the flour, stopping and scraping down the sides of the bowl as necessary. Then turn on the food processor and slowly pour in the water until a dough forms. Dough should be moist but stiff enough to hold shape. Adjust the flour and water if necessary. Remove the dough from the food processor, form it into a ball, and knead it for about 30 seconds until smooth. Let dough sit for about 20 minutes.
Divide the dough into 10 even balls for 8 inch tortillas. Press the dough balls into flat disks. On a flat un-floured surface, roll each ball into a very thin round circle, about 8 inches wide.
Heat a dry skillet over medium heat. Cook each tortilla about 30 seconds on one side, then 15 to 30 seconds on the other, until cooked through and faint light brown spots form on the second side.
Wrap in a dampened cloth and foil and keep warm in oven.