To make Caramel Pound Cake :

Center a rack in the oven and preheat the oven to 325 degrees F/160 degree C and grease with butter and dust lightly with flour a 10-inch fluted tube pan, making sure there are no clumps of butter or exposed areas in pan; set aside.

Take a bowl sift the flour, baking powder and salt and set aside.

In the another large bowl; cream 3 sticks of butter with using a hand mixer or stand mixer at medium speed for 2 minute until creamy and soft.

Add the light brown and white sugars and into to creamed butter and mix,stopping to scrape down the bowl now and then with a rubber spatula occasionally, until lightened and smooth, about 5 minutes.

Reduce speed to medium-low and Add in eggs, one at a time,beating for about 15 seconds after each addition and scraping down the bowl with a spatula as you go, until well blended. (Note : Do not overmix).

Reduce speed to low and add the flour mixture and 11/2 cups milk alternately, in 3 batches, beginning and ending with flour; beat until smooth, about 3 minutes total.

Scrape the batter into the prepared pan and bake in the center of the oven until a wooden skewer inserted in the center comes out clean, about 1 hour and 10 minutes. (Note : Do not overbake).

Remove from oven and let cake cool in the pan on a wire rack for at least 30 minutes. Loosen edges with a small knife, then turn onto rack to let cool completely.

To make Caramel Icing:

Melt butter in a large heavy saucepan over medium heat.

Add dark brown sugar and whisk constantly until mixture is bubbling and smooth and butter is completely incorporated, about 3 minutes.

Remove from heat and whisk in remaining 1/2 cup milk or whipping cream. Let mixture cool. Stir in the vanilla, then gradually add the confectioners' sugar and stir until well blended and smooth.

Transfer cake to a cake plate and ice with frosting. Let stand for at least 2 hours before slicing.