Mocha Coffee Cake

1. Preheat oven to 350 F (175 C).
2. Butter and flour 9 inch (23 cm) spring form pan.
3. Using an electric mixer, cream 3/4 cup butter and granulated sugar until light.
4. Add the eggs and vanilla and beat until fluffy.
5. In a separate bowl combine the flour, baking powder, baking soda and salt.
6. Add the dry ingredients to the egg mixture in 3 parts, alternating with the sour cream.
7. Mix well after each addition, scraping the bowl as necessary.
   
   
8. Dissolve the coffee in the hot water.
9. Remove 1/3 of the batter to another bowl and add the coffee mixture.
10. Combine the brown sugar, walnuts and 1/8 cup melted butter.
11. Spread half of the remaining batter in the prepared pan.
12. Cover with the coffee-flavored batter and then the brown sugar-walnut mixture.
13. Top with the remaining batter.
14. 
    
    Add topping then bake for 50 to 60 minutes or until cake tester inserted in the center comes out clean.

Combine the sugar and walnuts and sprinkle over the batter in the pan.

Combine the butter, sugar, cream, vanilla and instant coffee in a small saucepan over medium heat or in a microwave. Bring to a simmer and cook until the sugar dissolves. Pour over the warm cake. Cool the cake completely before removing it from the pan. Melt the chocolate in a double boiler or in the microwave and drizzle over the cooled cake. Store in a tightly closed container at room temperature for up to 4 days.