1: Prepare the Batter

1. 1. Preheat your oven to 350°F (175°C). Grease a 9×9-inch baking dish or line it with parchment paper.

1. 1. In a medium bowl, whisk together the flour, baking powder, baking soda, and salt.

1. 1. In a large mixing bowl, cream the butter and sugar until light and fluffy—this takes about 2-3 minutes.

1. 1. Add the eggs one at a time, beating well after each addition. Stir in the sour cream and vanilla extract.

1. 1. Gradually add the dry ingredients to the wet mixture, mixing until just combined. Avoid overmixing to keep the cake tender.

2: Make the Streusel Topping

1. 1. In a small bowl, combine the brown sugar, cinnamon, nuts (if using), and flour.

1. 1. Add the cold butter and cut it into the mixture using a fork or pastry cutter until it resembles coarse crumbs.

3: Assemble the Cake

1. 1. Spread half of the batter evenly into the prepared baking dish.

1. 1. Sprinkle half of the streusel topping over the batter.

1. 1. Add the remaining batter, spreading it gently to cover the streusel layer.

1. 1. Top with the remaining streusel.

4: Bake and Cool

• • Bake for 40-50 minutes, or until a toothpick inserted into the center comes out clean.

• • Let the cake cool in the pan for 10 minutes before transferring it to a wire rack to cool completely.

5: Prepare the Frosting (Optional)

• In a small bowl, whisk together:
  • 1 cup powdered sugar
  • 2-3 tablespoons milk or heavy cream
  • ½ teaspoon vanilla extract
• Mix until smooth, adjusting the consistency by adding more powdered sugar for a thicker glaze or more milk for a thinner drizzle.

6: Frost the Cake

• • • Once the cake has cooled completely, drizzle the frosting over the top using a spoon or piping bag. For a decorative finish, make zigzag patterns or spread it evenly across the surface.
    • Let the frosting set for a few minutes before slicing and serving.