01 - Combine bread flour, yeast, salt, and sugar in a large mixing bowl. Mix thoroughly to distribute evenly.
02 - Add warm water and olive oil to the dry ingredients. Stir until a shaggy dough forms.
03 - Knead by hand or with stand mixer fitted with dough hook for 5-7 minutes until smooth and elastic.
04 - Gently knead in chopped spinach and cottage cheese until well incorporated. The dough will be slightly sticky.
05 - Place dough in a lightly oiled bowl, cover, and let rise in a warm place for 1 hour until doubled in size.
06 - Preheat oven to 425°F. Line a baking sheet with parchment paper.
07 - Turn dough out onto a floured surface. Divide into 8 equal portions.
08 - Shape each piece into a ball, flatten to 1/2 inch thick. Poke a hole in center with thumb and gently widen to form a flattened ring about 4 inches wide.
09 - Arrange flagels on prepared baking sheet. Cover with towel and let rest for 15 minutes.
10 - Brush tops with beaten egg and sprinkle with seeds if using.
11 - Bake for 18-20 minutes until golden brown and cooked through.
12 - Let cool on a wire rack before serving.