Preheat your oven to 350°F (175°C). Grease a 9-inch springform pan and set aside. This ensures the cake does not stick and bakes evenly.

In a medium bowl, combine 2 cups flour, baking powder, baking soda and salt. Stir gently and set aside. This helps the cake rise properly.

In a large bowl, beat softened butter and granulated sugar with a mixer until light and fluffy. This gives the cake a tender, soft texture.

Add eggs one at a time. Beat well after each. Then add vanilla extract and mix until smooth. This adds moisture and flavor to the batter.

Stir in sour cream until fully combined. Mix on low speed if using a mixer. This makes the cake moist and soft.

Gradually add the dry flour mixture into the wet mixture. Mix gently until just combined. Do not overmix to avoid a dense cake.

In a small bowl, mix brown sugar, 1 tablespoon flour, cinnamon and chopped pecans. Cut in butter pieces until the mixture is crumbly. This forms the crunchy topping.

Spread half of the batter into the prepared pan. Sprinkle half of the topping over it. Add the remaining batter, then the rest of the topping. This creates layers of flavor.

Bake at 350°F for 45–50 minutes. Test with a toothpick in the center; it should come out clean. Cake should be golden brown on top.

Let the cake cool in the pan for 15 minutes. Remove sides of the springform pan and transfer to a cooling rack. Slice and enjoy warm or at room temperature.