In the bowl of your stand mixer, stir together the warm milk, yeast, and half of the sugar (¼ cup/50g). Set aside until the yeast is very foamy, about 5-10 minutes.

Once foamy, add in the eggs, vanilla, salt and remaining sugar (¼ cup/50g) and whisk until well combined. Add in 2 ¼ cups of flour (270g) and whisk together to create a smooth paste. Add the melted butter and mix once more.

Add another 2¼ cups of flour (270g) and attach a dough hook. Knead on low speed for about 1 minute, until a shaggy dough forms. Scrape down the sides of the bowl. Increase to medium-low speed and knead until the dough is smooth, mostly balled up around the dough hook, and does not stick to your finger when gently tapped, 5 to 7 minutes. (If it feels sticky or is still completely stuck to the sides of the bowl, scrape down the sides of the bowl, sprinkle in additional flour, 1 tablespoon at a time, around the edge of the bowl, and mix again for another minute. You may not use all of the extra ¼ cup)

Place the dough in a large, lightly oiled bowl, and turn to coat. Cover the bowl with plastic wrap and place it in a warm place (about 75°F) to rise until doubled in size, 1 hour 30 minutes to 2 hours.

After the dough has been rising for 1 hour, make the topping by whisking together the flour, and powdered sugar in a medium bowl. Add the soft butter in small pieces to the bowl, then add the vanilla. Work the mixture together by mashing with a fork and/or stirring with a spatula until a smooth paste forms. (You can also use a handheld mixer on medium-low speed to mix this together.)

If desired you can divide the mixture into batches and flavor or color them. To make them like I did, add 3 drops of pink gel food coloring to one portion for pink conchas, and leave the other portion plain for cream conchas. Continue to mash and stir the mixture until the coloring is evenly mixed into each. Cover with plastic wrap and set aside in a cool place until ready to use.

Line two large, rimmed baking sheets with parchment paper and set aside.

Turn out the risen dough onto a lightly floured surface. Divide the dough into 12 equal pieces (about 90g each). To shape each dough ball, place the dough on an unfloured surface. Pinch the edges into the center, then flip the pieces over. Cup your hand around the dough, and pinch your thumb and middle finger towards each other so your hand is surrounding the dough. Move your hand in small circles on the surface to create a roll shape. (This will tighten the dough into a small ball.) Place six rolls onto each lined baking sheet, leaving at least 3” between each. Cover each tray loosely with plastic wrap and set aside.

Portion out twelve 1½-tablespoon-sized balls (about 30g each) of the topping. Working one at a time, roll each into a neat ball shape with your hands. Flatten the ball, then place it between two, lightly floured parchment paper squares. Press with your hands or use a small rolling pin to roll the disc between the parchment to create a circle about 4” in diameter and 1/16” thick. Remove the top piece of parchment paper. If you have a 4” round cutter, cut the topping using the cutter to make a clean circle. If you don’t, freehand it with a small knife or pastry wheel, just to clean up the edges.

Drape this piece over the top of one of the dough balls (The topping should nearly or completely cover the balls but without touching the sheet tray. Trim off any parts that are touching the tray.) Repeat with the remaining pieces of topping.

Use a very sharp knife to cut the Concha pattern into the top (seashell shaped lines, about ½-inch apart). Score just through the topping, being careful not to cut through the bread. You can also cut a grid, or any other pattern you enjoy.

Cover loosely with plastic wrap and allow your conchas to rise for 30 minutes, or until well puffed and you see some of the dough between the cuts.

While the conchas are rising, preheat the oven to 350°F.

Bake at 350°F for 18 to 20 minutes or until the bottoms are golden. Transfer to a wire rack to cool completely, or enjoy warm.