Flaky wife cake with sweet winter melon filling is a traditional Cantonese pastry. A family recipe with buttery, layered crust and delicate sweetness.
Preheat the oven to 350°F (175°C). Line a baking sheet with parchment paper.
Combine all-purpose flour and cake flour in a bowl. Cut in 4 tbsp of butter until mixture resembles coarse crumbs. Add 1 tbsp butter and 2 tbsp powdered sugar, then knead briefly just until a soft dough forms. Divide dough into 6 equal pieces, cover, and let rest 30 minutes.
For the filling, mash winter melon preserves with dried coconut, maltose syrup, 1 tbsp powdered sugar, and salt. Mix until fully combined and sticky.
Roll each dough piece into a ball, then flatten into a 3-inch round. Place 2 tablespoons of filling in the center, gather edges, and pinch closed. Flatten gently into a disk about 1/2 inch thick.
Arrange cakes seam side down on the prepared sheet. Brush with beaten egg yolk for a shiny finish.
Bake for 22-25 minutes at 350°F until golden on top and flaky. Cool on the tray for 10 minutes before serving.