Cut the peaches in half and remove the stones. With a teaspoon remove some of the flesh from the centres. Chop this and place in a bowl with the crushed biscuits, liqueur. egg yolks, sugar, almonds and most of the butter and mix well.
Stuff each peach with the mixture and top each with a knob of butter. Put them on an oiled baking tray and cook in a moderately hot oven for 35-40 minutes.
Arrange the peaches on a serving dish and sprinkle with icing sugar to serve. Extra biscuits can be served alongside peaches.