Blackberry almond friands

I've been wanting to try making friands for ages - little cakes made from egg whites, icing sugar and almonds. I think they'd work well with other ground nuts like pistachios or hazelnuts too, and with different fruits or even chocolate. These are unbelievably light and delicious!

Ingredients 

4 egg whites
4oz butter, melted
3 ½ oz ground almonds
5oz icing sugar (plus extra for dusting)
2 ½ oz plain flour
100g blackberries (I use frozen)

Method

1. Preheat oven to 190°C.
2. Grease a 24 hole mini muffin tin.
3. In a large bowl, beat the egg whites until light and fluffy.
4. Add the butter and ground almonds to the egg whites, and sift in the icing sugar and flour. 
5. Fold together with a metal spoon until just combined.
6. Divide the mixture into the mini muffin tins and top each with one or two blackberries.
7. Bake for about 15 minutes or until they start to brown slightly.
8. Remove from the oven and leave to cool in the tin for 5 minutes, then turn out onto a wire rack to cool completely. 
9. Serve dusted with a little extra sifted icing sugar.