01 - Combine bread flour, yeast, salt, and sugar in a large mixing bowl. Mix thoroughly to distribute all ingredients evenly.
02 - Pour warm water and olive oil into the dry mixture. Stir with a wooden spoon until a shaggy, rough dough forms.
03 - Knead by hand on a floured surface or with a stand mixer using dough hook for 5 to 7 minutes until smooth and elastic.
04 - Gently knead chopped spinach and drained cottage cheese into the dough until evenly distributed. The dough will feel slightly sticky.
05 - Place dough in a lightly oiled bowl, cover with plastic wrap or damp towel, and let rise in a warm, draft-free area for 1 hour until doubled in size.
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 - Form each portion into a smooth ball, then flatten to 1/2 inch thickness. Press your thumb through the center and gently stretch to form a 4-inch flattened ring.
09 - Arrange shaped flagels on the prepared baking sheet. Cover loosely with a clean towel and let rest for 15 minutes.
10 - Brush the tops of each flagel with beaten egg using a pastry brush. Sprinkle sesame seeds or poppy seeds evenly over the surface.
11 - Bake for 18 to 20 minutes until golden brown on top and cooked through. The internal temperature should reach 190°F.
12 - Transfer flagels to a wire cooling rack. Let cool completely before slicing, toasting, or serving.