Preheat your oven to 180°C (350°F). Line a rectangular baking tray (approximately 12x16 inches) with parchment paper, ensuring the edges are well covered to prevent sticking. In a large bowl, whisk the eggs and sugar using a hand mixer on high speed for 5–6 minutes until the mixture is pale, thick, and tripled in volume. This step is crucial for achieving a light and airy sponge.

Add the vanilla extract to the egg mixture and gently fold it in. Sift the flour, baking powder, and salt into the bowl in small batches. Carefully fold the dry ingredients into the egg mixture using a spatula, ensuring you maintain the batter’s fluffiness. Avoid overmixing, as this will deflate the sponge.

Pour the batter onto the prepared tray and spread it evenly using an offset spatula. Tap the tray gently on the counter to release any air bubbles. Bake in the preheated oven for 10–12 minutes, or until the sponge is golden and springs back when touched lightly.

While the cake is baking, prepare a clean kitchen towel and sprinkle it generously with powdered sugar. This prevents the cake from sticking when you roll it.

Once baked, immediately invert the sponge onto the prepared towel. Carefully peel off the parchment paper. Starting from one short edge, roll the sponge tightly with the towel into a spiral. Allow it to cool completely in this rolled shape. This step ensures the cake will retain its flexibility later.

Unroll the cooled sponge gently. Spread a generous layer of dulce de leche evenly across the surface, leaving a small border around the edges. Sprinkle the chopped walnuts or shredded coconut over the dulce de leche if desired.

Carefully roll the sponge back into a tight log, this time without the towel. Ensure the seam is placed underneath to maintain the roll’s shape. Wrap the roll in plastic wrap and refrigerate for at least 30 minutes to set.

Dust the Brazo de Reina with powdered sugar just before serving. For an extra touch, drizzle with additional dulce de leche or top with whipped cream. Slice into even portions and serve with coffee or tea. For a traditional Chilean experience, pair with a cup of strong café negro.