Preheat oven to 350 degrees Grease 2 (9 inch) pie pans or springform pans with 1 tablespoon olive oil each, then dust lightly with flour.
In a medium bowl, beat eggs. Whisk in yogurt until smooth. Crumble in feta. Mix in flour, baking soda, and salt if using.
In a small bowl, stir 1/4 cup olive oil with melted butter.
Lightly dust work surface with flour. Unroll the phyllo sheets with short end facing you. Gently brush the top sheet with the butter mixture. Add 2-3 tablespoons of the feta yogurt in a thin line across the short side nearest you. Tightly roll up the phyllo sheet to the other short side. Place seam side down with one end in the center and spiral around in a circle. Repeat with remaining phyllo sheets, continuing to wrap them around the center until you reach the edge of the pie pan. Fill the other pie pan.
Drizzle the top of the pies with remaining butter mixture and lightly with seltzer water to barely moisten.
Bake in preheated oven until the top is golden brown, 45 minutes to 1 hour. Allow to cool 10-20 minutes before drizzling with honey and serving.