Fill a medium saucepan with water and bring it to a simmer. In a heatproof bowl, whisk blood orange juice, zest, sugar, salt and eggs yolks. Place the bowl over the pot of simmering water and whisk the mixture until it thickens, for about 10 minutes.

Remove from the heat, transfer the curd to a shallow bowl and whisk until it cools down to a room temperature. Whisk in pieces of butter to create a nice and shiny emulsion. Cover the curd with a plastic wrap and let it set in the fridge for 1-2 hours.

Preheat the oven to 100 C/200 F. Line a baking sheet with parchment paper.

In a bowl of stand mixer fitted with a whisk attachment place egg whites, pinch of salt and 1/3 of sugar. Start whisking on a medium speed until egg whites becomes frothy. Slightly increase the speed and continue whisking until whites start to hold the trail.

With a mixer running, slowly add another 1/3 of sugar. Increase the speed and whisk until the meringue starts to turn glossy. Slowly add the remaining sugar and continue whisking for another 2-3 minutes. Meringue should be very stiff and glossy.

Sift 1/3 of powdered sugar on top of whipped whites. Using a rubber spatula, carefully fold powdered sugar into meringue. Continue adding the remaining sugar and folding it into the meringue, making sure the whites are smooth and there's no lumps of sugar left. Transfer the meringue to a baking sheet. Using a back of the spoon form it to a desired shape.

Place the sheet into the oven and bake for about 1 hour, or until the meringue feels dry, light and hollow. Turn off the oven and let the meringue cool down there.

When the meringue is completely cool, add the layer of blood orange curd on top and spread evenly using a back of the spoon. Add blood orange slices and enjoy it right away!