Preheat the oven to 375°F and line a baking sheet with parchment paper or a silicone baking sheet.
In a large bowl whisk together the flour, baking powder, salt, and red pepper flakes.
In a medium skillet add the spinach and olive oil. Cook until the spinach is mostly wilted. Remove to a cutting board and chop. Add the chopped cooked spinach to the flour mixture and work it in with your hands until it’s evenly incorporated. Work the feta cheese in the same way.
Using a pastry cutter or a cheese grater, cut the butter into the flour. Work it in with your hands until coarse crumbles about the size of a pea are formed.
You can chill for a few minutes at this point or go ahead and pour in the milk. Gently work the milk into the dough until it just comes together.
Turn the dough out onto a floured surface, knead two to three times, and then pat it out to about 3/4” thick. Cut the dough into 20-24 2” circles and place them on the prepared baking sheet.
Whisk together the egg and water and brush the tops of the scones with the egg wash. Bake for 20 minutes.
Notes
If your scones are not turning out buttery and tender there are typically a few culprits:
Keeping ingredients cold is crucial for perfect, tender scones. I often put the bowl back in the fridge after cutting the butter into the dry ingredients, and I keep the milk refrigerated up until I pour it in.
Over-mixing - be sure to mix the wet and dry ingredients until they are JUST combined!
You might need a liiiiiitle more milk. If the dough seems too dry ahead of shaping it, add in a tablespoon of milk at a time.
Try measuring your flour by weight. I am a spoon-and-level girl at heart, but I also live in a pretty humid climate. If your scones seem dry, try measuring your flour by weight. 1 cup of all-purpose flour = 4.25 ounces. 3 cups = 12.75 ounces.