Preheat oven to 350F and grease an 8-inch square pan.
Melt the chocolate and butter together in the microwave and let cool for 5 minutes.
Combine sugar, syrup, coffee, buttermilk, egg, vanilla and chocolate mixture in a large bowl. Beat with electric mixer on medium speed until blended.
Stir together flour, baking soda and salt in small bowl. Gradually add flour mixture into chocolate mixture until blended. Spread batter in prepared pan.
Bake 30 to 35 minutes or until toothpick inserted in center comes out clean. Cool completely in pan on wire rack.
Chocolate Maple Mousse
For mousse, melt chocolate chips in large microwave-safe bowl on HIGH 1 minute or until melted and smooth when stirred. Stir in syrup and about ½ cup cream until blended. Let cool for 5 minutes. Add remaining 1 ½ cups cold cream. Beat mousse mixture with electric mixer on medium-high speed until stiff. Spread over cooled cake. Top with fresh fruit if desired.