Suspiro: Puerto Rican Meringue Frosting for Bizcocho

• Prep30 min
• Cook10 min
• Total40 min
• Serves24

Ingredients

Suspiro

• 130 g egg whites (from about 4 large eggs)
• 300 g sugar (1 1/2 cups)
• 1/4 tsp cream of tartar, or 1 tsp fresh lime juice
• 1 pinch salt
• 1 tsp clear vanilla extract

To finish

• 1 two-layer 20 cm (8 in) bizcocho, filled and completely cool (see tips)
• Rainbow sprinkles

Instructions

1. Wash and dry the mixing bowl and butterfly whisk very well and wipe both with a paper towel dampened with lime juice or vinegar. Separate the eggs one at a time over a small cup, so one broken yolk does not spoil the whole batch: even a trace of yolk or fat keeps the whites from whipping.
2. Insert the butterfly whisk, add the egg whites, sugar, cream of tartar (or lime juice) and salt and whip 10 min/70°C (160°F)/speed 3.5. Heating the whites to 70°C (160°F) makes them safe to eat without baking, and the acid helps the meringue hold its peaks. Rub a drop between your fingers: it should feel smooth, with no sugar grains.
3. Remove the measuring cup and whip 12 min/speed 4 without heat, until the suspiro is very thick, glossy and snow white, holds stiff peaks and the bowl feels cool or barely warm. A warm meringue is runny and slides down the sides of the cake, so give it a few more minutes if needed.
4. Add the vanilla and whip 30 sec/speed 4. Set the filled, completely cool bizcocho on a cake stand or serving plate and brush off any loose crumbs.
5. Spoon a big mound of suspiro on top and spread it to the edges and down the sides with an offset spatula or the back of a large spoon, until the whole cake is covered in a thick layer.
6. Make the peaks: touch the back of a spoon to the suspiro and lift it up quickly, all over the cake, for those classic soft swirls.
7. Scatter the sprinkles right away, while the surface is still soft, so they stick. Serve the same day, kept in a cool, air-conditioned room. Refrigerate leftovers, covered: the suspiro gets softer in the fridge, but it is still delicious the next day.

Tips

• Humidity is the enemy of meringue: sugar pulls water from the air, so on a muggy Florida day the suspiro softens and can form little beads of syrup. Make it with the air conditioning on, avoid rainy days when you can, frost the cake close to the party and keep it out of the fridge until then, where it picks up moisture. Cream of tartar gives the steadiest suspiro on humid days.
• To tint it pastel, add a tiny bit of gel color on a toothpick with the vanilla: pink, baby blue, lilac or mint green. Use gel, not liquid color, which adds water and softens the meringue. For a different flavor, swap the vanilla for 1/2 tsp almond or coconut extract, or fold in the finely grated zest of 1 lime by hand.
• Fill the bizcocho before covering it, and make the filling first so it has time to cool. For guava, cook 200 g guava paste in cubes with 60 g water (1/4 cup) 5 min/90°C (195°F)/speed 3, until smooth. For pineapple, cook one 567 g (20 oz) can of crushed pineapple with its juice, 50 g sugar (1/4 cup) and 16 g cornstarch (2 tbsp) 8 min/100°C (212°F)/speed 2, until thick. Let it cool completely and spread it between the layers, leaving a 1 cm (1/2 in) border so it does not leak into the suspiro.