Coffee Crunch Cake

Combine 1 1/2 cups sugar, coffee and corn syrup in saucepan at least 5
inches deep. Bring mixture to boil and cook to 310F on candy thermometer or
hard-crack stage (small amount of mixture dropped into cold water will
break with brittle snap). Remove syrup from heat, immediately add soda and
stir vigorously just until mixture thickens and pulls away from sides of
pan. (Mixture will foam rapidly when soda is added. Do not destroy foam by
excessive beating.) Immediately pour foamy mass into ungreased 9-inch
square metal pan (do not spread or stir). Let stand without moving until
cool. When ready to garnish cake, knock hardened mixture out of pan and
crush between sheets of waxed paper with rolling pin to form coarse crumbs.
Split cake into 4 equal layers. Combine cream, remaining 2 tablespoons
sugar and vanilla in chilled bowl and beat until stiff. Spread about 1/2 of
cream between layers and remainder over top and sides of cake. Sprinkle
generously with crushed topping. Refrigerate until ready to serve.