Let the butter, eggs, and sour cream stand at room temperature for 30 minutes. Preheat oven to 350 degrees F. Grease and flour 12 individual fluted tube pans; set aside.

In a large bowl combine flour, ground tea leaves, baking powder, salt, and soda; set aside.

In a very large mixing bowl beat butter with an electric mixer on medium-high speed for 1 to 2 minutes. Add granulated sugar; continue beating 5 minutes. Beat in the eggs, 1 at a time, scraping sides of bowl after each addition. Beat in vanilla. (Mixture may appear curdled.) Alternately add flour mixture and sour cream to butter mixture, beating on low speed after each addition until combined. Spoon batter into prepared pans, filling two-thirds full.

Bake 25 minutes or until pick inserted near center comes out clean. Cool in pans on racks 10 minutes. Remove; cool on racks.

Split cakes in half. Place bottoms on plates; spread with curd. Add tops. Sprinkle powdered sugar. Makes 12 cakes (24 servings).

*Test Kitchen Tip: For 4 teaspoons ground Earl Grey tea leaves, open bags with finely ground tea leaves (5 bags) or use mortar and pestle to finely grind loose Earl Grey tea leaves; measure 4 teaspoons.)