Heat the oven to 400°F while you assemble the dish. A fully heated oven lets the broth begin steaming promptly once the covered pan goes in.
Pour the coconut milk into your baking dish and add 1 tablespoon curry paste, garlic, soy sauce, sesame oil, and the optional fish sauce or lime juice if using. The liquid will look streaky until you blend the seasonings together.
Whisk thoroughly, taste the broth, and work in up to two additional tablespoons of curry paste if the heat suits you. Look for an evenly colored mixture without concentrated lumps of curry paste.
Fold the spinach through the broth and spread the coated leaves across the bottom. Moistened leaves settle beneath the dumplings and wilt into the sauce as they cook.
Set the frozen dumplings into the broth with their pinched folds facing down, then spoon liquid across every exposed top. The wrappers should look damp rather than dry before you cover the pan.
Seal the dish with a lid or tightly fitted foil and bake for 20 minutes with 14 dumplings in a shallow pan, or 30 to 40 minutes in a deeper dish or with more dumplings. Bubbling sauce around the edges shows that the liquid is hot, but the filling still needs a doneness check.
Check that the dumplings are tender and cooked through, continuing the covered baking as needed or leaving the dish uncovered for the final 5 minutes if you want thicker broth. The wrappers should feel soft, and some become slightly translucent, although wrapper appearance alone does not confirm that the filling is done.
Take the dish out of the oven and scatter chili crisp, cilantro, scallion greens, and sesame seeds over the dumplings. The finished dish should have plump wrappers, steaming curry broth, and fresh, contrasting toppings.