Spinach and Matzo Pie

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 ⅓ cup dill, ¾ tsp. kosher salt, and ½ tsp. freshly ground black pepper.

Purée cottage cheese in a blender with milk, eggs, nutmeg, and ½ tsp. each kosher salt and freshly ground black pepper until smooth. Reserve 2 cups in a bowl and stir remainder into spinach with 1 cup feta.

Stack matzos in a deep dish and pour reserved cottage-cheese mixture over them. Let stand 15 minutes to soften.

Arrange 2 soaked matzos side by side in a generously oiled 13x9x2-inch (3-quart shallow) baking dish. Pour in half of spinach filling. Cover with 2 more matzos, then pour in remaining filling. Put remaining 2 matzos on top and pour any remaining cottage-cheese mixture over them. Sprinkle with remaining ½ cup feta.

Bake, uncovered, until golden and set, 30 to 35 minutes. Cool 10 minutes, then serve sprinkled with remaining 2 Tbsp. dill. Do ahead: Pie can be assembled (but not baked) 1 day ahead and chilled, covered.