Ricciarelli originate in Siena, where I believe they are sold around Christmas and given as gifts. My daughter found an old River Cafe recipe in a Sunday newspaper magazine several years ago, and has tweaked it with practice. Below is the recipe in her own words; it has been emailed to nearly everyone who's ever tried them.
1. Blanch and peel 300g almonds. I put them in a bowl, boil the kettle, cover them with hot water, and leave for around 5 minutes before draining and squeezing off the skins. Some will be stubborn; put these to one side and pop them back in the bowl, covering them in the hottest water your kitchen tap will supply for a minute. Repeat until all almonds have been blanched. If you're super lazy, you can skip this step by using sliced almonds (in which case reduce the roasting time and keep an eye on them as they can't go brown) or pre-blanched almonds. It's a lot more expensive, though, and almonds aren't the cheapest of ingredients.
2. Roast the almonds in an oven for 12 minutes at 180C. (I prefer to roast them in three goes of 4 minutes apiece, shaking furiously between each go.) Allow to cool, but leave the oven on.
3. Bung 8 tbsps plain sugar, the cooled almonds, and the zest of half a lemon into the food processor. Blend till it looks like sand.
4. Beat 2 egg whites to firm peaks. Add 60g sugar to the beaten egg whites, and beat back to firm. You can do this by hand, but it's a million times easier with an electric whisk. But if you do it by hand, you've earned the right to eat more biscuits. Your call.
5. Dump the blender mixture into the beaten egg white. Before folding with a metal spoon, add half a teaspoon each of vanilla and almond extracts. Fold, but not too much. You want to introduce the mixes to each other, not marry them off.
6. Cover a baking sheet with greaseproof paper.
7. Wet your hands, then scoop a normal eating spoon of mix into your hands. Roll into a ball, pop on the baking sheet, then smash flat. But not too flat. This is not the time for your best Incredible Hulk impression. The batch should make 20 ricciarelli, so I usually find myself making some huge ones to start with, and then stealing mix off them so I can bulk up the weedy ones at the end. I end up re-wetting my hands about every five.
8. The recipe says bake 20 minutes, but I say 16 – I cook them in two lots of 8 minutes, rotating the tray 180-degrees at the end of the first 8 minutes. I have a fan oven, so you might want to adjust based on your equipment. You may as well spend the cooking time watching the ricciarelli to ensure they don't burn - it's not *that* long.
9. Allow to cool – but only enough that the icing sugar won’t melt – and then dust with icing sugar. They keep for about 4-5 days in a sealed box, but they’re nicest eaten still warm.