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1
For frosting: Combine all ingredients in heavy large saucepan.
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2
Whisk over medium heat until chocolate melts and mixture is smooth and just begins to bubble, about 8 minutes.
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3
Refrigerate until just thick enough to spread, stirring occasionally, about 1 1/2 hours.
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4
Meanwhile, prepare cake: Preheat oven to 350F (180C).
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5
Line 15 1/2x10 1/2x1 inch baking sheet with foil, leaving overhang.
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6
Grease foil.
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7
Sift 1/2 cup sugar, cocoa powder, cake meal and potato starch into medium bowl.
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8
Combine egg whites and salt in large bowl.
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9
Using handheld mixer, beat whites until soft peaks form.
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10
Gradually add 1/2 cup sugar; beat until stiff but not dry.
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11
Using same beaters, beat yolks and 1/2 cup sugar in another large bowl until thick, about 2 minutes.
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12
Gradually beat in oil, then nondairy creamer.
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13
Add dry ingredients; beat just until blended.
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14
Fold whites into yolk mixture in 3 additions.
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15
Spread batter in prepared pan.
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16
Bake until tester inserted into center comes out dry and cake feels firm to touch, about 20 minutes.
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17
Cool cake in pan rack.
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18
Freeze cake until firm, about 30 minutes.
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19
Using foil as aid, lift cake onto work surface.
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20
Cut cake crosswise into 3 rectangles, each about 5x10 inches.
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21
Slide large spatula under 1 cake rectangle; transfer to platter.
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22
Spread 23 cup forsting over.
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23
Top with second layer.
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24
Spread 23 cup frosting over.
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25
Top with third layer.
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26
Spread very thin layer of frosting over top and sides of cake to coat thinly and anchor crumbs.
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27
Refrigerate 15 minutes to set thin coat of frosting.
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28
Spread remaining frosting decoratively over cake.
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29
Refrigerate until cold, about 4 hours.
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30
(Can be made 3 days ahead.
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31
Cover loosely with foil; keep refrigerated.)
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32
Cover top of cake with chocolate shavings and garnish with mint, is desired.
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33
Cut crosswise into slices and serve.
