Step 1

Make the curry paste: Puree lemongrass, cilantro, garlic, scallions, chiles, ginger, lime zest and juice, coriander, cumin, peppercorns, and 1 teaspoon salt in a food processor until smooth.

Step 2

Make the curry sauce: Puree spinach, coconut milk, and 1/4 cup plus 1 tablespoon curry paste in blender until smooth.

Step 3

Preheat oven to 375 degrees. Make the filling: Bring curry sauce to a simmer in a medium straight-sided skillet. Whisk in flour, and simmer until thickened, about 2 minutes. Add zucchini, and cook until slightly tender, about 5 minutes. Add chicken, and season with salt and pepper. Cook until zucchini is tender and chicken is cooked through, about 5 minutes.

Step 4

Make the topping: Transfer filling to a 9-by-12-inch (8-cup) baking dish. Brush 1 sheet of phyllo with butter. Layer phyllo sheet over filling, crumpling slightly. Repeat with remaining phyllo and butter, leaving space between each sheet to vent. Sprinkle top with salt. Bake until phyllo is golden and filling is bubbling, about 25 minutes. Garnish with basil.