Preheat oven to 350°F. Spray a 12-cup bundt pan with cooking spray.
In a large bowl, cream together shortening and sugars. Add eggs and beat by hand.
In another bowl, sift together flour, baking powder, cinnamon, and salt.
In a small bowl, blend together milk and baking soda and add to creamed mixture, alternately with the dry ingredients. Fold in apples.
Pour batter into prepared pan.
Mix together ingredients and sprinkle on cake.
Bake for 45 to 50 minutes, or until a tester inserted into the center comes out clean. Remove from oven and let stand 10 to 15 minutes. Invert cake onto a serving plate.
Put brown sugar and butter into a microwave-safe bowl and cook for 1 to 2 minutes, or until bubbling. Remove and stir in milk, then add powdered sugar and beat by hand or with hand mixer until smooth. Drizzle over cake.