Preheat oven to 350 F.
Grease and flour two 9-inch springform cake pans. Set aside.
In a medium bowl, mix the grated carrot with lemon juice, lemon zest, and walnuts. Set aside.
In a large bowl, beat the melted butter, sour cream, honey, eggs, vanilla, and brown sugar until well blended.
Add the flour, cinnamon, baking soda, baking powder, and salt and mix until blended.
Stir in the grated carrot mixture and stir until well blended. Evenly divide the batter into the two cake forms.
Bake for 35 minutes or until a wooden skewer inserted into the centre comes out clean. Let cool completely on a wire rack before frosting.
For the frosting, beat together the cream cheese, butter, and icing sugar. Frost the cake and chill for 30 minutes before serving.