Preheat oven to 350 degrees. Line 24 muffin cups with liners.

Put all the cake ingredients, except for the black walnuts, in a mixing bowl and beat on low until moistened, then beat on medium speed for 2 minutes. Stir in the black walnuts and fill muffin cups 2/3 full. Bake in preheated oven for 16-18 minutes, or until a toothpick inserted in the center of one comes out clean. Cool on wire rack in the pans for 10 minutes, then take out of the pans and cool completely on rack.

For frosting, beat the cream cheese and butter together until creamy. Beat in everything but the milk until well blended and fluffy. If it is too thick, you can add milk 1 teaspoon at a time until you get your desired consistency. Frost the cooled cupcakes.