Preheat your oven to350 °F.
Lightly grease an18x13-inch sheet pan with cooking spray.
For the cake: in abowl, add the flour, sugar and salt and mix well.
In a saucepan, addthe butter and cook until melted.
Add the cocoa powderand stir to combine.
Stir in the boilingwater and bring to a boil.
Remove from the heatand place the butter mixture over the flour mixture.
With a wooden spoon,stir the mixture and set aside to cool slightly.
In a small bowl, addthe buttermilk, eggs, vanilla extract and baking soda and beat until wellcombined.
Add the buttermilkmixture into the bowl of the flour mixture and mix until just combined.
Place the mixture into the prepared sheet panand with a spatula, spread in an even layer.
Bake for about 20 minutes or untila toothpick inserted in the center comes out clean.
Remove the sheet panfrom the oven and place onto a wire rack to cool for about 10 minutes.
Then invert the cakeonto the wire rack to cool slightly before frosting.
For the frosting: ina small saucepan, add the butter over medium heat and cook until melted.
Stir in the cocoapowder and remove from the heat.
Add the powderedsugar, milk and vanilla extract and stir until well combined.
Add the almonds and stirto combine.
Place the frostingover the warm cake evenly.
Cut the cake into desired-sized pieces and serve.