Let's cook.
Preheat your oven to 375°F (190°C). Lightly grease a 9x13 inch baking dish or a round baking pan.
In a large bowl, combine the chopped fresh spinach, crumbled feta cheese, plain yogurt, eggs, and 1/4 cup of olive oil. Mix well until all ingredients are evenly distributed. Season with 1/4 teaspoon of black pepper.
Carefully unroll the phyllo dough. Take one sheet of phyllo and lay it flat on a clean surface. Brush lightly with olive oil.
Place a second sheet of phyllo on top of the first, then brush it lightly with olive oil as well. Repeat this process with a third sheet of phyllo, brushing it with olive oil.
Spread about 1/6 of the spinach and feta filling evenly along one long edge of the layered phyllo sheets. Roll the phyllo tightly into a long cylinder.
Carefully coil the cylinder into a spiral shape and place it in the prepared baking dish. Repeat steps 3-5 with the remaining phyllo sheets and filling, arranging the spirals next to each other to form a large, continuous swirl.
Brush the top of the assembled phyllo swirls with any remaining olive oil. Bake for 30-35 minutes, or until the phyllo is golden brown and crispy.
Remove from the oven and let cool for 5-10 minutes before slicing and serving warm.
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