Place the stainless steel inner pot inside the Instant Pot®. Press Saute, add 1 tbsp butter and brown the shrimp, season with salt and pepper; when they change color, turn them over. Once cooked, remove and set aside. Peel the shells and set aside.
In the same saute step, add 2 tbsp butter. Once melted, add the fish loins on the skin side, season with salt and pepper, turn them over. Once cooked, remove and set aside.
While still in Saute, add 2 tbsp butter, stir fry the shallot, leek and garlic. Add the tomatoes, add a drizzle of olive oil, season with salt and pepper. Add the water, saffron and bay leaf, using a wooden spatula, scrape the bottom of the pot to release all the flavors. Add the shrimp shells, clams and mussels. Press Cancel.
Close and lock the Instant Pot® lid. Make sure the steam release handle is turned to Sealing. Press Soup/Broth and set time to 20 Minutes. Once done, strain the broth and check for salt.
On a deep dish, serve on chunk of fish, shrimp, mussels and clams. Add the broth, cover with the puff pastry dough, baste with egg and sprinkle with a pinch of salt. Bake at 355°F (180°C) for 20 Minutes or until the pasta is golden.