The spinach needs to be dry
Break up the squeezed spinach before adding it to the eggs. Small tufts distribute more easily than a compact lump. The quick turn in the skillet removes a little more moisture and helps the spinach mix through the liquid.
Let the cheese help with the seasoning
Feta brings salt as well as tang, so the recipe begins with a modest amount of added salt. Different brands vary. Taste a small piece of cheese while preparing the dish, then adjust the amount of added salt if yours is especially salty.
Use a block of feta and crumble it yourself when possible. Some pieces can remain a little larger so the cut portions have pockets of cheese. For vegetarian cooking, choose feta made with vegetarian rennet.
A firm center without a hard edge
An 8-inch square dish gives this quantity enough depth to cut into portions. A much larger dish makes a thin bake with a shorter cooking time; a deeper, smaller one changes the center cooking time in the other direction.
Check the center with a thermometer and let the dish rest briefly before slicing. The egg mixture should be set throughout, including the center. Serve with a salad, sliced fruit, or toast chosen for your own dietary needs.
