Coconut macaroon and chocolate mousse tart

Method

1. Heat the oven to 180°C/160°C fan/gas 4. For the macaroon tart case, put the egg whites into a large, very clean mixing bowl and whisk with an electric mixer to stiff, dry peaks. Whisk in the sugar, a tablespoon at a time, whisking back to stiff peaks after each addition. Next, whisk in the cream of tartar and vanilla extract, then fold in the desiccated coconut.
2. Spoon the coconut mixture into the tart tin, then press it into the base and up the sides, making sure the case is firmly packed and even. Run a palette knife over the top to give a clean edge. Put the tin on a baking sheet, line the case with scrunched-up non-stick baking paper and fill with baking beans or uncooked rice. Bake for 20 minutes, then remove the paper and beans/rice and bake for 5-10 minutes more. It’s ready when the edges are golden and the inside is dry. Set aside to cool.
3. Meanwhile, make the filling. Put all the chocolate, the sugar, butter, rum and 75ml of the cream into a  large heatproof bowl set over a pan of steaming (not simmering) water on a low heat, making sure the bowl doesn’t touch the water. Don’t stir until melted, then stir gently to mix. Take off the heat and leave to cool a little while you whip the cream.
4. In a large bowl, whisk the cream to soft peaks. Pour the chocolate mixture into the whipped cream and fold it in using a balloon whisk until evenly combined but no more. Pour it into the case and shake gently to level. Chill for 3-4 hours or overnight.
5. About 30 minutes before serving, take the tart out of the fridge. Loosen the case from the tin using the tip of a knife, then remove the tart. Transfer to a serving plate, top with coconut flakes, then slice to serve.