1/2 medium onion, finely chopped
olive oil
250g frozen chopped spinach, thawed
1/3 cup chopped dill
200g cottage cheese
1
cup whole milk
2 eggs
85g feta, crumbled - 3/4 cup
3-4 matzos
Preheat oven to 400°F with rack in middle. Cook onion in oil in a large heavy skillet over medium heat, stirring occasionally, until golden, 12 to 15 minutes.
Meanwhile, put spinach in a sieve and press out as much liquid as possible.
Add spinach to onion and cook, stirring occasionally, 5 minutes. Remove from heat and stir in dill, salt and pepper.
Purée cottage cheese in a blender with milk, eggs, and salt and pepper until smooth. Reserve 1 cup in a bowl and stir remainder into spinach with 1/2 cup feta.
Stack matzos in a deep dish and pour reserved cottage-cheese mixture over them. Let stand 15 minutes to soften.
Place 1 soaked matzos in a generously oiled shallow baking dish.
Pour in half of spinach filling. Cover with 1 more matzo, then pour in remaining filling. Put remaining matzo on top and pour any remaining cottage-cheese mixture over them. Sprinkle with remaining feta.
Bake, uncovered, until golden and set, 20-25 minutes.