The secret to great Media Lunas lies in the laminated yeast dough (masa hojaldrada) and working quickly with the butter so it doesn't melt into the dough. Unlike French croissants, which are buttery and more neutral, Media Lunas are sweet and often have a sugar syrup glaze immediately after baking, which gives them an irresistible shine and sweetness.
When laminating the dough, it is crucial to keep it cold, so the process of folding and rolling must be alternated with resting in the refrigerator.
In a small bowl, dissolve the yeast with a tablespoon of sugar in the warm milk. Let activate for 5-10 minutes until foam appears.
In a large bowl, mix the flour, remaining sugar, salt, egg, vanilla, and activated yeast mixture. Knead to form a soft, elastic dough. Kneading should take about 5–10 minutes until the dough is smooth.
Wrap the dough in plastic wrap and place it in the refrigerator for 30 minutes.
Cut the cold butter into slices and shape it into a square about 15x15 cm. You can press it between two pieces of plastic wrap or baking paper. The butter should be malleable enough but still cold.
Roll out the dough into a larger square (about 30x30 cm). Place the butter square diagonally in the centre of the dough so that its corners touch the middle of the dough's sides. Fold the corners of the dough over the butter to completely cover it, creating a smaller square.
Roll out the butter-filled dough into a rectangle (approximately 20x50 cm).
First Fold (Triple Fold): Fold the rectangle like a letter (left third to the centre, then the right third over it). Wrap in plastic wrap and chill for 45 minutes.
Repeat the rolling and triple folding two more times (a total of 3 folds), always turning the dough 90 degrees before rolling and chilling for 45 minutes between each fold. The dough is ready after the last chilling.
Roll out the dough into a thin rectangle, about 3–4 mm thick.
Cut the rectangle into isosceles triangles (with a base of about 8–10 cm).
Make a small slit (about 1 cm) on the wide side of each triangle. Gently stretch the dough and roll it up from the base towards the tip. Bend the ends inward to form a crescent shape (Media Luna).
Place on a baking sheet lined with parchment paper. Let the Media Lunas proof in a warm place for about 60 minutes until they double in volume. Brush with whisked egg mixed with a splash of milk.
Preheat the oven to 185 °C (365 °F).
Bake for 18–20 minutes until the Media Lunas are golden brown and puffed up.
Glaze (Almíbar): Meanwhile, mix the sugar and water in a small pot and bring to a boil. Boil for about 3–4 minutes until the syrup thickens slightly. Let it cool.
Immediately after removing from the oven, brush each Media Luna with the syrup. This gives them their characteristic shine and sweetness. Serve warm.