Preheat oven to 325ºF.
In an electric mixer with paddle attachment, cream together butter, shortening, sugar until light and fluffy. Add eggs one at a time and continue to beat.
In a separate bowl sift together dry ingredient, twice. Add the dry ingredients to the creamed butter mixture, alternating with the milk and mix well in a low speed each time. Add vanilla and stir well.
Turn the cake batter in a greased floured tube pan or bundt pan and bake for 60-75 minutes or until the toothpick comes out clean when tested.
Cool cake in a pan for 15 minutes, then remove from the pan and completely cool on a wire rack.
To make caramel icing: melt butter in a saucepan over med-low heat, stir in brown sugar, and he cream. Remove from heat and stir until smooth.
Return to heat and bring to boil for 1 minute.
Let the mixture cool. Add the confectioner's sugar and vanilla, and beat until smooth. Add more cream if needed.