3: Pour 30 g clarified butter into a large frying pan on high heat. When hot, add the apples and 2 tablespoons caster sugar. Sauté the apples until they soften, but without browning. You can flambé them with 3 tablespoons Calvados (apple liqueur) if you wish, but this is not essential. Set aside.
4: Beat 90 g egg white to the "stiff peak" stage, adding 75 g caster sugar towards the end while still beating, to make the raw meringue mix.
5: Take a little of the meringue and add this to the lemon custard. Mix in with a soft spatula.
6: Then add this mixture to the rest of the meringue and fold in gently until evenly mixed and light. Note:Mixing in 2 stages like this helps to combine the two different textures of the meringue and confectioner's custard.
7: Add the apple pieces and mix again gently. Preheat the oven to 390°F (200°C).
8: Put the mixture into a buttered gratin dish and bake for about 10 minutes.
9: After 5 minutes, sprinkle the top with caster sugar and change your oven setting to "grill" (broiler) to brown the top (if your grill is separate, leave the dish in the oven for a couple of minutes longer, then brown briefly under the grill).
Remarks
Use eating apples, rather than tart cooking apples for this, as the lemon in the confectioner's custard already adds a note of acidity. You will notice that the cooking time is very short - just 10 minutes - 5 minutes of which are under the grill. The clafoutis only really needs to be heated through and the top browned.