Serves: 20 conchas
To make the dough:
1) Heat the milk to 43 degrees C. Add the milk and yeast in the bowl of a heavy duty mixer. Let rest about 10 mins. Add the flour, sugar, egg, salt, and vanilla and, using the dough hook, mix until well combined. Add the butter in 3 equal additions and mix until well combined. Knead in the mixer on low, about 5 mins. Divide the dough into 7g balls.
To make the topping:
1) With an electric mixer, cream the lard and icing sugar together in a bowl. Add the flour, baking powder, and vanilla and mix until combined. Roll out the topping on a floured surface into a thin sheet, about 30mm thick. Use a biscuit cutter or knife to cut out circles that are large enough to cover the top of the dough balls.
2) Preheat the oven to 160C/Gas 3.
3) Top each dough ball with a circle of topping and sprinkle them with sugar. Using the back of a pairing knife, scratch the image of a shell on the top of each concha. Arrange on a baking tray lined with parchment paper. Let rise until doubled in size, about 45 mins. Bake the conchas about 5 to 7 mins.