Make the dough. In a bowl, whisk eggs, olive oil, and salt with water, plus more as needed. Gradually mix in certified gluten-free oat flour and tapioca starch or cornstarch until a soft, slightly sticky dough forms. Add a touch more water if too dry. Cover and rest for 20 minutes.
Make the filling. Heat olive oil and add fresh spinach, roughly chopped in batches until wilted, about 4-5 minutes. Let cool slightly, then squeeze out excess liquid.
Combine the filling. Mix the cooked spinach with the cottage cheese, feta, egg, salt in a bowl.
Roll the dough. Preheat oven to 180°C (350°F). Divide the rested dough into 4 equal pieces. Roll each between two sheets of parchment paper into thin rounds, about the size of your baking dish.
Layer the pie. Lightly oil a baking dish. Place one dough round on the bottom, brush with a little 1tablespoons olive oil, for sautéing and brushing. Spread a layer of the spinach-cheese filling on top. Repeat layering dough and filling, finishing with a dough round on top.
Bake. Brush the top layer with remaining 1 tablespoons olive oil, for sautéing and brushing. Cover loosely with foil and bake for 40 minutes, then remove foil and bake another 15-20 minutes until golden on top.
Cool and slice. Let the pie rest for 10 minutes before slicing into squares or wedges to serve.
Notes
Nena'sPro tip: I baked this one in a standard bread loaf pan instead of a traditional baking dish. It makes for clean, sliceable pieces and honestly looks beautiful once you cut into it and see the layers. If you don't have a loaf pan, a regular baking dish works fine too; just reduce the covered bake time slightly since the layers won't be stacked as deep.
This pie keeps well in the fridge for a few days in an airtight container. In fact, I think the flavor and texture are even better the next day once everything has had time to set.
I haven't tried freezing this one myself, and given the egg-and-cheese filling, I'd be a little cautious about how it holds up texture-wise. If you do try freezing it, I'd love to hear how it turns out!