01 - Combine bread flour, instant yeast, 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 and olive oil into the dry ingredients. Stir with a wooden spoon until a shaggy, rough dough begins to form and all flour is incorporated.
03 - Knead by hand on a lightly floured surface or use a stand mixer with dough hook attachment for 5-7 minutes until dough becomes smooth, elastic, and passes the windowpane test.
04 - Gently fold chopped spinach and drained cottage cheese into the dough. Continue kneading briefly until evenly distributed. The dough will feel slightly sticky due to the cheese moisture.
05 - Transfer dough to a lightly oiled bowl, turning once to coat all surfaces. Cover with plastic wrap or a damp towel and place 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 risen dough onto a lightly floured surface. Using a bench scraper or knife, divide into 8 equal portions, approximately 4 oz each.
08 - Form each portion into a smooth ball by tucking edges underneath. Flatten each ball to 1/2-inch thickness. Press your thumb through the center and gently stretch to create a 4-inch ring, maintaining flattened shape.
09 - Arrange shaped flagels on prepared baking sheet, leaving 2 inches of space between each. Cover with a clean kitchen towel and let rest at room temperature for 15 minutes to puff slightly.
10 - Brush the tops and sides of each flagel generously with beaten egg using a pastry brush. Sprinkle sesame or poppy seeds evenly over the tops while egg wash is still tacky.
11 - Bake at 425°F for 18-20 minutes until deep golden brown, rotating the baking sheet halfway through for even coloring. The bottoms should sound hollow when tapped.
12 - Transfer baked flagels to a wire cooling rack. Allow to cool completely for at least 30 minutes before slicing or serving to prevent gummy texture.