Preheat the oven to 400 degrees.
Melt the butter over a double boiler.
Once the butter is melted stir in the chocolate until the mixture is smooth.
Whisk in the eggs, egg yolks, and sugar until combined
Fold in the cassava flour and salt.
Divide the batter into four ramekins that have been lightly buttered and dusted with cocoa powder and placed on a baking sheet.
Bake the lava cakes for 9-13 minutes. If you like them more gooey stay closer to 9 and if you want them less gooey keep them closer to 13.
Remove the cakes from the oven and revert them on to serving plates.
Top with desired toppings and enjoy!