Step 1Heat the oven to 350 degrees. Coat a 9-inch square baking pan with nonstick cooking spray and set the pan on a foil-lined baking sheet.
Step 2Roast the semolina in a dry skillet over medium heat, stirring, until the color changes, 10 minutes. Combine the coconut milk, enough water to fill 1 coconut milk can, evaporated milk, eggs, sugar and bananas in a large pot and heat over medium heat until barely simmering, about 4 to 5 minutes. Slowly pour in the roasted semolina, mixing well to avoid lumps. Cook over medium heat, stirring constantly, until thick. Addthe butter or margarine while stirring.
Step 3Pour the batter into the pan and bake until a toothpick inserted in the center comes out clean and the top is evenly golden brown, 1 hour. Sprinkle the top with the poppy seeds. Place under the broiler and broil 2 minutes. Cool to room temperature, cover and let stand overnight. Cut into diamonds to serve. Refrigerate any leftovers. Reheat to room temperature before serving.