Stir together first 6 ingredients in a small bowl. Set aside.
Beat butter and granulated sugar at medium speed with an electric mixer until well blended. Add eggs, one at a time, beating well after each addition. Add sour cream, beating until well blended.
Sift together 1 1/4 cups flour and next 3 ingredients. Add to butter mixture, beating until well blended. Stir in vanilla. Spoon half of batter into a greased and floured 9-inch cake pan. Sprinkle evenly with 2/3 cup brown sugar mixture; spoon remaining half of batter evenly over brown sugar mixture in pan; sprinkle evenly with remaining brown sugar mixture.
Bake at 350° for 35 to 40 minutes or until a wooden pick inserted in center comes clean. Let cool in pan on a wire rack; garnish, if desired.
*1 tablespoon Bigelow French Vanilla tea leaves may be substituted.
Note: For testing purposes only, we used The Tea Room's Vanilla Jasmine Tea for the cake.