Stir together 1 1/3 cups flour and brown sugar in a small bowl. Cut butter into flour mixture with a pastry blender or fork until crumbly; stir in pecans. Set aside.
Beat cream cheese at medium speed with an electric mixer until smooth; add granulated sugar and 1 tablespoon flour, beating until blended. Add egg and 1/2 teaspoon vanilla, beating until blended.
Spoon Chocolate Velvet Cake Batter evenly into 2 greased and floured 9-inch springform pans. Dollop cream cheese mixture evenly over cake batter, and gently swirl through cake batter with a knife. Sprinkle reserved pecan mixture evenly over cake batter.
Bake at 350° for 45 minutes or until set. Cool on a wire rack.
Whisk together powdered sugar, milk, and remaining 1/2 teaspoon vanilla extract. Drizzle evenly over tops of coffee cakes.