01 -
Heat oven to 190°C / 375°F. Cook shells in a large pot of boiling water for 2 minutes less than the packet time. Drain carefully and let cool enough to handle.
02 -
Squeeze thawed spinach very dry in a clean towel. Chop it finely and mix with ricotta, egg, Parmesan, garlic powder, salt and pepper.
03 -
Spread 500 g marinara over the base of a 23 × 33 cm baking dish. Spoon the filling evenly into the 24 shells and arrange open-side up.
04 -
Spoon the remaining 200 g sauce around the shells and scatter mozzarella over the top. Cover loosely with foil.
05 -
Bake 25 minutes, uncover and bake another 10–15 minutes until bubbling and golden. Check that the center filling is piping hot and the egg mixture is fully set.
06 -
Rest 10 minutes before serving; the shells should stay tender with a creamy, set filling.
07 -
Cool leftovers promptly and refrigerate within two hours for up to three days. Reheat covered until hot throughout.