Preheat the oven to 350°F (175°C)
Grease and flour a cake pan or baking dish
Mix flour, sugar, baking powder, and salt in a bowl
Cut in butter until the mixture is crumbly
Whisk together eggs, milk, and vanilla in a separate bowl
Combine the wet and dry ingredients until just mixed
Pour half of the batter into the prepared pan
Mix brown sugar, cinnamon, and chopped nuts for the filling
Sprinkle the filling over the batter
Add the remaining batter on top
Mix flour, brown sugar, cinnamon, and butter for the crumb topping
Sprinkle the crumb topping evenly over the batter
Bake for 30 to 40 minutes
Check doneness with a toothpick
Let the cake cool before slicing
Serve plain or with coffee glaze if desired