Preheat oven to 350F (or 180C). Grease a 9x5-inch loaf pan and line it with parchment paper to make lifting out the cake easier. Set aside.
In the bowl of a stand mixer fitted with the paddle attachment cream butter and sugar together at medium speed until pale and fluffy about 4 minutes.
Add eggs one at a time and beat well for about 30 seconds after adding each egg. Add salt, vanilla extract, and sour cream.
In a small bowl combine flour and baking powder. With the stand mixer running on low add 1 cup of the flour mixture, beat for 30 seconds. Then add the second cup and beat for 30 seconds.
Transfer 1/3 of the batter into another bowl. Add the raspberry jam and beat until combined. Add 2-3 drops of gel food color if desired.
Add the lemon juice to the other dough and beat until combined.
Add a layer of white batter to your loaf pan. Then alternate between pink and white dough. Use a knife to swirl the doughs together but don't overdo it or you will end up without a marble effect.
Bake for 60-65 min or until a skewer inserted in center of the pound cake comes out clean with only a few crumbs attached. If your pound cake browns too quickly cover it with aluminum foil.
Let the cake cool in the pan for 15 minutes. Then lift it out of the pan and let it cool completely on a cooling rack.
To make the icing: Beat the cream cheese for about 20 seconds on medium speed until softened. Add the powdered sugar and mix until well combined.
Spread the frosting on top of the cooled cake and serve! Store leftovers in the fridge.