Preheat oven to 180°C (160°C fan-forced), lightly grease a 25cm round loose bottom fluted tart tin and line the base with baking paper.

Place almonds and sugar in a food processor, pulsing until mixture resembles a fine crumb.

Add melted butter and vanilla extract, pulsing until mixture is well combined and starts coming together.

Pour almond mixture into prepared tart tin, pressing firmly and evenly into the bottom and sides of the tin.

Place tart tin on a baking tray in preheated oven and bake for 15 minutes.

Remove tart shell from oven and allow to cool completely.

For the chocolate mousse, pour boiling water into a large saucepan, about a quarter full and sit a large bowl on top, making sure the bottom does not touch the water.

Add chocolate, stirring occasionally until chocolate melts. Remove bowl from heat and allow to cool slightly.

Place eggs and sugar together in a large mixing bowl and beat with an electric mixer until thick and mousse like.

Add egg mixture to the melted chocolate, folding gently to combine.

In a large clean mixing bowl, whisk cream using an electric mixer until soft peaks form.

Add a third of the whipped cream to the chocolate mixture, folding gently to combine, to help loosen the mixture. Add remaining cream, folding gently until combined.

To assemble tart, spoon chocolate mousse into the cooled tart shell, spreading evenly with the back of the spoon.

Place in refrigerator and chill for 2 hours, to allow mousse to set.