Mexico's iconic shell-shaped sweet bread with a crunchy sugar topping is a breakfast essential. This family-favorite pan dulce is a beloved, soft treat enjoyed with coffee or hot chocolate.
Warm the milk until just lukewarm (about 100°F), then mix with instant yeast and let sit for 5 minutes.
Combine flour, sugar, and salt in a large bowl. Add the yeast-milk mixture, softened butter, and eggs. Mix into a sticky dough.
Knead the dough on medium-low speed for 7–8 minutes until smooth and elastic. Cover and let rise in a warm spot until doubled, about 1 hour.
While rising, prepare the topping: Cream butter and powdered sugar together, stir in flour and vanilla until a smooth paste forms. For a chocolate variation, divide and mix cocoa into a portion.
Divide risen dough into 8 balls. Place on a lined baking sheet. Flatten a portion of topping into a disk and gently press over each ball.
Use a knife to lightly score a shell pattern into the topping. Cover loosely and let buns rise again, 30–40 minutes, until puffy.
Bake at 350°F (175°C) for 18–20 minutes. The topping should crackle but not brown deeply. Cool slightly before serving.