Preheat the oven to 350°F (175°C).

Grease a 9-inch round cake pan.

In a large mixing bowl, whisk together the flour, sugar, baking powder, and salt.

Cream the softened butter until light and fluffy.

Add the milk, eggs, and vanilla extract to the butter and mix until well combined.

Gradually add the dry mixture to the wet ingredients, stirring gently until just combined.

In a small bowl, mix brown sugar, cinnamon, and chopped nuts for the streusel topping.

Pour half the batter into the prepared pan, sprinkle half the streusel mixture on top, layer the remaining batter, and finish with the rest of the streusel.

Bake for 30-35 minutes, or until a toothpick inserted in the center comes out clean.

Let the cake cool for at least 10 minutes before slicing.