Preheat oven to 350 degrees. Line 2 baking sheets with parchment paper and set aside.
Layer phyllo dough in 2 stacks of 6 sheets, brushing between each sheet with melted butter. Cut each stack in half lengthwise and each strip into thirds to make 12 rectangles. Cut each rectangle on the diagonal to make 24 triangles. Place triangles on prepared baking sheets and bake until they are golden, about 4 to 6 minutes.
Place 3 tablespoons lemon custard in the center of half of the triangles. Top with remaining triangles. Warm a serving platter and place sporcamusi on top. Sprinkle with confectioners' sugar and serve immediately.