"This is a very easy-to-make dish. It's a lovely flavored curry which is accompanied by cilantro yogurt. If you're pressed for time, you can make the filling and yogurt hours earlier so all you're left to prepare is the phyllo pastry. Hope you like it."
Heat oil in a large skillet over medium-high heat. Add chicken, onion, and garlic; cook and stir until chicken is no longer pink, 5 to 10 minutes. Season with salt and pepper. Add curry paste, stirring well. Add coconut cream and mix well. Reduce heat and simmer until thickened, about 15 minutes.
Stir 1/2 of the cilantro into the curry mixture. Remove skillet from heat and let cool completely.
Preheat the oven to 350 degrees F (175 degrees C).
Brush each sheet of phyllo dough with melted butter and stack. Cut the phyllo stack into 6 square pieces. Whisk egg and milk in a bowl to make egg wash.
Spoon some of the curry mixture into the center of 1 square, ensuring you leave a large border. Brush the border with egg wash and fold into a triangle. Pinch the edges securely and place on a baking sheet. Repeat with remaining phyllo and curry mixture. Brush tops of the triangles with egg wash.
Bake in the preheated oven until golden brown, about 30 minutes.
Make the cilantro yogurt while the triangles bake. Combine remaining cilantro, Greek yogurt, lemon juice, and cayenne pepper in a bowl. Serve with the triangles.