Kiki's herring and pumpkin pie (Kiki's Delivery Service)

Steps

1. Cut the red kuri squash or pumpkin flesh into pieces, then steam or cook it in a covered saucepan until it can be easily mashed with a fork.
2. Mash the squash while still warm with the butter, cream, a touch of nutmeg, pepper, and very little salt; the puree should be thick, sweet, and not watery.
3. Sauté the sliced onion in the olive oil with the garlic and thyme until translucent and slightly sweet-smelling.
4. Flake the mild smoked herring fillets, removing any visible bones, then mix them with the sautéed onion and béchamel; the filling should remain creamy but firm enough not to make the pastry soggy.
5. Line a tart pan or oval baking dish with the puff pastry, prick the bottom, then spread the pumpkin puree in an even layer.
6. Spread the herring filling evenly over the pumpkin, smooth gently, then cover with the second puff pastry, sealing the edges well with your fingertips.
7. Cut out fish shapes from the pastry scraps, place them on top, add the black olives as a decoration, then brush with the egg yolk thinned with a little milk.
8. Bake in a very hot oven until the pie is deeply golden, puffed, and the filling is bubbling slightly around the edges.
9. Let rest out of the oven before serving, giving the filling time to set and the smoky flavors time to meld with the pumpkin.