To make the pastry, place the flour, butter, icing sugar and cocoa powder in a food processor and process until the mixture resembles fine breadcrumbs. Add iced water and process until pastry just comes together. Turn on to a clean work surface lightly dusted with flour and lightly knead until just smooth. Cover with plastic wrap and place in the fridge 30 mins to rest.
Divide pastry into 4 portions. Roll each portion, on a clean work surface lightly dusted with flour until 3mm thick. Line four 10cm heart shaped, fluted tins with removable bases with the pastry and trim the edges. Prick pastry bases with a fork. Place in the freezer for 20 mins to chill.
Preheat the oven to 200°C. Place tart tins on a baking tray. Line tins with baking paper and fill with pastry weights or rice. Bake for 10 mins. Remove the paper and weights or rice. Bake for a further 5 mins or until pastry is dry to touch. Remove from oven and set aside to cool completely.
Meanwhile, to make the caramel filling, stir the condensed milk, butter, vanilla essence and brown sugar in a saucepan over low heat until smooth. Bring to a simmer. Reduce heat to low and cook, stirring for 5 – 7 mins or until thickened and slightly darker in colour. Remove from heat. Divide caramel among tart shells, smoothing the surface. Set aside to cool completely.
To make the ganache, place the cream and chocolate in a small saucepan. Stir over low heat for 2-3 mins or until melted and smooth. Pour over the caramel. Place in the fridge to chill until set. Serve the tarts topped with toasted almonds and whipped cream.