Pre-heat the oven to 170°C then grease and line an 8 inch square baking tin.
In a large bowl whisk together the flours, ground walnuts, baking powder and salt and set aside.
In a separate mixing bowl beat the butter and sugar for a few minutes until light and fluffy.
Add the eggs one at a time, mixing after each addition then add the vanilla.
Fold in the flour mixture and mix in until just combined.
Pour the cake batter into the tin then place in the oven and bake for about 30 minutes or until an inserted cocktail stick comes out clean.
Remove the cake from the oven, turn out of the tin and allow to cool for 30 minutes.
Meanwhile prepare the soak by whisking the evaporated milk, condensed milk, cream, cinnamon and cardamom seeds in a saucepan over medium heat until it is just warm. Remove from the heat.
Place the cake in a dish with high sides, poke several holes into the cake with a cocktail stick then spoon the glaze over.
Cover the dish with cling film then refrigerate overnight.
Remove the cake from the fridge to take the chill off whilst you prepare the toppings.
Begin with the caramelised walnuts by the placing the walnuts on a baking tray in an oven pre-heated to 180°C for 5 minutes until toasted. Remove and set aside.
In a smallish saucepan pour the caster sugar evenly into one layer and heat over a medium heat. The sugar will slowly melt, beginning at the sides. Carefully shake the saucepan every so often so the sugar melts evenly, do not stir. As soon as all the sugar has melted drop in a pinch of salt.
Prepare a baking sheet with baking parchment before pouring the walnuts into the molten sugar and stir in with a silicone spatula. Working quickly make sure all the walnuts are coated in sugar then tip onto the baking parchment, spreading out into an even layer. Leave to cool then chop finely.
To make the whipped latte cream, whip the cream for a few minutes with the coffee powder and icing sugar until thick and cloudlike.
Finally, carefully remove the cake from its dish, spread the whipped cream over, cut into 16 squares then sprinkle over the caramelised walnuts.