01 - In a large mixing bowl, combine bread flour, yeast, salt, and sugar. Mix thoroughly to distribute all ingredients evenly.
02 - Pour in warm water and olive oil. Stir with a wooden spoon until a shaggy, rough dough forms.
03 - Knead by hand on a floured surface or with a stand mixer fitted with a dough hook for 5–7 minutes, until dough becomes smooth, elastic, and pulls away from the sides of the bowl.
04 - Gently knead chopped spinach and drained cottage cheese into the dough until evenly distributed. The dough will feel slightly sticky due to the vegetables and cheese.
05 - Place dough in a lightly oiled bowl, turning once to coat. Cover with plastic wrap or a damp towel and let rise in a warm, draft-free area for 1 hour, or until doubled in volume.
06 - Preheat oven to 425°F. Line a baking sheet with parchment paper and set aside.
07 - Turn risen dough onto a lightly floured surface. Divide into 8 equal portions using a bench scraper or knife.
08 - Shape each portion into a smooth ball. Flatten each ball to about 1/2 inch thickness. Press your thumb through the center and gently stretch with fingers to form a 4-inch flattened ring.
09 - Arrange shaped flagels on the prepared baking sheet, leaving 2 inches of space between each. Cover with a clean towel and let rest for 15 minutes.
10 - Brush tops of flagels generously with beaten egg using a pastry brush. Sprinkle with sesame or poppy seeds if desired.
11 - Bake for 18–20 minutes, rotating the baking sheet halfway through, until flagels are deeply golden brown and sound hollow when tapped on the bottom.
12 - Transfer flagels to a wire rack and let cool for at least 15 minutes before slicing or serving.