Chocolate Espresso Marble Coffee Cake

• Prep time: 25 mins | Bake time: 45–50 mins
• Serves: 10–12

Ingredients

• Crumb Topping:
  • $\frac{1}{2}$ cup all-purpose flour
  • $\frac{1}{3}$ cup brown sugar
  • $2$ tbsp unsweetened cocoa powder
  • $\frac{1}{4}$ cup chopped hazelnuts or walnuts
  • $3$ tbsp unsalted butter, melted
• Cake Batter:
  • $2$ cups all-purpose flour
  • $1\frac{1}{2}$ tsp baking powder
  • $\frac{1}{2}$ tsp baking soda
  • $\frac{1}{2}$ tsp salt
  • $\frac{1}{2}$ cup unsalted butter, softened
  • $1$ cup granulated sugar
  • $2$ large eggs
  • $1$ tsp vanilla extract
  • $\frac{3}{4}$ cup sour cream
  • $\frac{1}{2}$ cup strong brewed coffee or espresso, cooled
• Chocolate Swirl:
  • $3$ tbsp unsweetened cocoa powder + $2$ tbsp warm water (mixed into a smooth paste)

Instructions

1. Preheat oven to 350°F (175°C) and line a 9×9-inch baking pan with parchment paper.
2. Make the topping: Stir flour, brown sugar, cocoa powder, and nuts together. Mix in melted butter until clumps form.
3. Make the batter: Whisk flour, baking powder, baking soda, and salt.
4. Beat butter and sugar until light, then add eggs and vanilla.
5. Combine the sour cream and cooled coffee in a measuring cup. Alternate adding the flour mixture and the coffee-sour cream mixture to the butter.
6. Scoop out $\frac{3}{4}$ cup of the plain batter and fold the cocoa paste into it.
7. Pour the plain batter into the pan, dollop the chocolate batter on top, and swirl gently with a knife. Top with the chocolate crumb mixture.
8. Bake for 45–50 minutes until set.