Combine flour and salt in a food processor. Add in butter and use the pulse to break up the butter into pea-size pieces. Add in 1 tablespoon of cold water at a time, blending after each addition until the dough is coming together, and moist.

Place dough onto a floured surface and shape it into a ball. Cover with plastic wrap and place in the refrigerator for 1 hour.

Take 6 ramekins, or one pie plate, and grease with butter. Preheat oven to 375 degrees.

Whisk eggs, heavy cream, salt and pepper in a bowl until very smooth. Take dough from refrigerator and lay out on a floured surface. Use a rolling pin or sturdy cup to roll out the dough. Cut dough into 6 ramekin-sized circles, or one large circle, if using a pie plate. Place dough in ramekins or pie plates.

Layer on a row of spinach leaves on top of the dough, sprinkle with 1/6th of the cheese, and fill 3/4 of the way with the egg mixture. Repeat for all ramekins.

Bake in preheated oven for 35 - 45 minutes, when you can insert a knife or toothpick, and it comes out clean.