Delicate sweetheart cake with crispy, flaky pastry and sweet filling is a Cantonese classic. A family treat with romantic history and fresh, buttery layers.
Preheat the oven to 375°F. Line a baking tray with parchment paper to prepare for baking.
Make the pastry: In a mixing bowl, combine 2 cups all-purpose flour with 1 stick softened unsalted butter and 4 tbsp lard. Rub together until coarse crumbs form, then drizzle in just enough water to bring together a soft, pliable dough. Cover and let rest for 30 minutes.
Prepare the filling: Dice 8 oz sweetened winter melon finely. Mix with 1 cup desiccated coconut, 2 tbsp white sesame seeds, 6 tbsp powdered sugar, 2 tbsp honey, and 0.5 tsp salt in a saucepan over low heat for 3–4 minutes, stirring constantly until sticky and well combined. Allow filling to cool to room temperature.
Divide rested dough into 12 equal portions. Roll each into a ball, then flatten into a 4-inch disc about ⅛-inch thick to form the pastry shells.
Place a heaping spoonful of cooled filling in the center of each disc. Gently gather the edges and seal to encase the filling. Flatten each filled ball slightly and place seam-side down on the prepared baking tray.
Brush the tops of the cakes with beaten egg yolk. Optionally, sprinkle with extra sesame seeds for added texture.
Bake in the preheated oven for 25–30 minutes, rotating tray halfway through, until golden and crisp. Cool on a wire rack before serving for maximum flakiness.