Preheat oven to 350º F and lightly grease a 13×18-inch cake pan with butter or non-stick spray.
In a medium bowl, whisk together dry ingredients (flour, baking soda and salt).
In a separate, large bowl, stir together sugar, water, melted butter, sour cream, eggs, and vanilla and almond extracts until combined.
Gradually stir dry ingredients into wet ingredients until just incorporated, then pour mixture into greased cake pan.
Place pan in oven and bake for 18-21 minutes, or until toothpick inserted in center comes out clean.
While cake is baking, whisk together all frosting ingredients except for the sliced almonds until frosting is smooth and desired consistency is reached.
Remove cake from oven and let cool 5 minutes, then pour icing over the cake and cover with sliced almonds. Let set, then slice into squares and enjoy.