Coffee Cake with Sour Cream

Ingredients

• 12 tablespoons unsalted butter at room temperature
  
• 1 1/2 cups granulated sugar
  
• 3 extra-large eggs at room temperature
  
• 1 1/2 teaspoons pure vanilla extract
  
• 2 tablespoons of instant coffee powder
• 1 1/4 cups sour cream
  
• 2 1/2 cups cake flour 
  
• 2 teaspoons baking powder
  
• 1/2 teaspoon baking soda
  
• 1/2 teaspoon kosher salt
  

For the streusel:

• 1/4 cup light brown sugar
  
• 1/2 cup all-purpose flour
  
• 1 1/2 teaspoons ground cinnamon
  
• 1/4 teaspoon salt
  
• 3 tablespoons cold unsalted butter, cut into pieces
  
• 3/4 cup chopped walnuts, optional
  

Directions

• Preheat the oven to 350 degrees F. Grease and flour a pan.
  
• Cream the butter and sugar in the bowl for 4 to 5 minutes, until light. Add the eggs 1 at a time, then add the vanilla and sour cream. In a separate bowl, sift together the flour, baking powder, baking soda, coffee powder and salt. With the mixer on low, add the flour mixture to the batter until combined. 
  
• For the streusel, place the brown sugar, flour, cinnamon, salt, and butter in a bowl and pinch together with your fingers until it forms a crumble. Mix in the walnuts, if desired.
  
• Spoon half the batter into the pan and spread it out with a knife. Sprinkle with 3/4 cup streusel. Spoon the rest of the batter in the pan, spread it out, and scatter the remaining streusel on top. Bake for 50 to 60 minutes, until a cake tester comes out clean.