Preheat oven to 300F/150C; grease and flour pans. Line bottoms with rounds of wax paper and grease paper.

In a medium saucepan combine flaxseeds with 1 cup water. Bring to a boil and simmer 3-5 minutes, until mixture is thickened and resembling egg whites in consistency. Let cool. Strain by squeezing through cheesecloth - this requires some elbow grease! Total volume should be about 3/4 cup. If the volume is less, add water to make 3/4 cup.

Combine chocolate in a bowl with hot coffee. Let mixture stand, stirring occasionally, until chocolate is melted and mixture is smooth.

Into a large bowl sift together flour, sugar, cocoa, baking powder, baking soda, and salt. In another bowl with an electric mixer, beat flax liquid until thickened and foamy. Slowly add oil, yogurt mixture, vanilla, and melted chocolate mixture to flax, beating until well combined. Add dry ingredients and beat on medium speed until just combined well. Divide batter between pans and bake in middle of oven until a tester inserted in the center comes out clean, about 50 minutes.

Cool layers completely in pans on racks. Run a thin knife around edges and invert layers onto racks. Carefully remove wax paper.

For ganache frosting:

In a medium saucepan bring soy milk, sugar, and syrup to a boil over medium low heat, whisking until sugar is dissolved. Remove from heat and add chocolate, whisking until melted. Cut margarine into pieces and add to frosting, whisking until smooth.

Transfer to a bowl and cool, stirring occasionally, until spreadable (chilling may be necessary).

Spread frosting between cake layers and over top and sides.

If you don't want the extra work of straining the boiled flax, you could substitute 3/4 cup of pureed silken tofu. For a richer cake, I used melted cocoa butter in place for some of the oil. This recipe also bakes up well in a bundt pan, and as cupcakes (adjust baking times).