HEAT oven to 350°F Spray 10-inch tube pan with flour no-stick cooking spray. Combine 2 1/4 cups brown sugar, sugar, 1 cup butter, shortening and 2 teaspoons vanilla in large bowl; beat until light and fluffy. Add eggs 1 at a time, beating well after each addition.
COMBINE flour, baking powder and salt in medium bowl; mix well. Add flour mixture to butter mixture alternately with milk, beating well after each addition. Stir in pecans. Spread batter in prepared pan.
BAKE 1 1/4 hours or until toothpick inserted in center comes out clean. Cool 10 minutes. Remove from pan. Cool 1 hour or until completely cooled.
MELT 1/4 cup butter in small saucepan over medium-low heat. Add 1/2 cup brown sugar; cook 2 minutes, stirring constantly. Add 1/4 cup milk; bring to a boil, stirring constantly.
REMOVE saucepan from heat. Stir in vanilla. Gradually stir in powdered sugar; blend until smooth. Drizzle over cooled cake.