Walnut Espresso Coffee Cake

The Steps

1. Preheat the oven to 350 degrees and butter a 9 inch square pan.
2. Make the topping by combining all ingredients in a bowl and whisking together with a fork. Set aside.
3. To make the cake, sift the flour, baking powder, baking soda and salt. Set aside.
4. Add the butter and sugar to the bowl of a stand mixer fitted with the paddle attachment. Mix for 3 minutes until light and fluffy.
5. Add the eggs, one at a time, mixing between each addition.
6. In a small bowl, combine the warm water and espresso powder. Once the espresso has dissolved, whisk in the sour cream.
7. Add ½ of the flour mixture into the mixing bowl and mix until just incorporated. Add ½ of the sour cream mixture to the bowl and mix until just incorporated. Repeat with remaining flour and sour cream mixtures.
8. Pour the batter into the prepared pan and spread the crumble evenly over the top.
9. Bake for 35 to 40 minutes or until a toothpick inserted in the center comes out clean.
10. While the cake cools, make the glaze by dissolving the espresso powder in the water then whisking in the powdered sugar
11. Pour the glaze over the cooled cake before serving.