01 - Combine bread flour, instant yeast, fine sea salt, and granulated sugar in a large mixing bowl. Mix thoroughly to ensure even distribution of yeast and salt throughout the flour.
02 - Pour warm water (110°F) and olive oil into the dry mixture. Stir with a wooden spoon or hands until a shaggy, rough dough begins to form and all flour is incorporated.
03 - Knead the dough by hand on a lightly floured surface or with a stand mixer fitted with dough hook for 5-7 minutes. Work until the dough becomes smooth, elastic, and passes the windowpane test.
04 - Gently fold the chopped spinach and drained cottage cheese into the dough. Knead just until evenly distributed—the dough will become slightly sticky due to the cottage cheese moisture.
05 - Place the dough in a lightly oiled bowl, turning once to coat all sides. Cover with plastic wrap or a damp towel and let rise in a warm, draft-free area for 1 hour until doubled in bulk.
06 - Preheat oven to 425°F. Line a large baking sheet with parchment paper and set aside.
07 - Turn the risen dough onto a lightly floured surface. Divide into 8 equal portions using a bench scraper or sharp knife.
08 - Roll each portion into a smooth ball, then flatten to approximately 1/2 inch thickness. Press your thumb through the center to create a hole, then gently stretch and widen the opening to form a 4-inch flattened ring.
09 - Arrange shaped flagels on the prepared baking sheet, leaving 2 inches between each. Cover with a clean kitchen towel and let rest for 15 minutes to relax the gluten.
10 - Brush the tops of each flagel generously with beaten egg using a pastry brush. Sprinkle with sesame or poppy seeds immediately after brushing if desired.
11 - Bake at 425°F for 18-20 minutes until flagels develop a deep golden-brown color and sound hollow when tapped on the bottom. Rotate the baking sheet halfway through for even browning.
12 - Transfer baked flagels to a wire cooling rack. Let cool completely for at least 30 minutes before slicing or serving to prevent gumminess.