Ingredients:

2 Unbleached All-Purpose Flour
1 Granulated Sugar
2 Granulated Sugar
1 Table Salt
10 Unsalted Butter
1 Baking Powder
1/2 Baking Soda
3/4 Buttermilk
1 Egg
2 Vanilla Extract
3/4 Walnuts
1/2 Brown Sugar
1 Ground Cinnamon
1/2 Allspice

Directions:

Adjust oven rack to center position and heat oven to 350°.
Generously grease bottom and lightly grease sides of 10-inch springform pan and dust with flour.
With electric mixer, mix flour, sugar, and salt in large mixing bowl until blended.
Cut in butter until mixture resembles coarse crumbs.
Remove 1 cup of crumbs to separate bowl.
Mix baking powder and soda into mixture remaining in large mixing bowl.
Add buttermilk, egg, and vanilla; mix well until batter is thick, smooth, fluffy, and frostinglike, 1 1/2- 2 minutes.,
Using a rubber spatula, scrape batter into prepared pan and smooth top.
Add nuts, brown sugar, cinnamon and allspice to reserved crumbs; toss with a fork or your hands until blended.
Sprinkle crumbs over batter, pressing lightly so that mixture adheres.
Bake cake until center is firm and cake tester comes out clean, 50- 55 minutes. TIP: Do not insert a toothpick to test for doneness until center is firm when pan is shaken.
Transfer cake to rack; remove pan sides.
Let cake cool completely, about 2 hours, before serving.,
When completely cooled, cake can be slid off pan bottom onto serving plate.