Begin by roasting the chocolate. Preheat the oven to 120 celsius (250 Fahrenheit) and add the chocolate into a small baking dish and place in the oven for 60 minutes, stirring every 10 minutes, until a deep caramel colour. Sprinkle the salt over the chocolate and stir to combine. Set aside to cool slightly.
Increase the oven to 170 degrees celsius (340 Fahrenheit) and line a 24cm square baking tin with baking paper. Place the white chocolate and butter in a heat proof bowl. Place a saucepan of water over a medium high heat and bring to a simmer. Turn the heat off and cover with the bowl containing the chocolate and butter. Stir until melted and smooth.
Add the beaten eggs to the melted chocolate mixture, along with the ground almonds and sugar and mix to combine. Pour the mixture into the prepared baking tin and bake for 25 to 30 minutes.
Allow to cool completely before cutting into squares.
Use a good quality white chocolate that contains cocoa butter and not vegetable oil. The higher the percentage of cocoa butter the better. 25% or more is best.