Preheat oven to 350° F (180°C). For the Cupcakes, mix flour, cocoa powder, baking soda and salt. Set aside. Beat butter and granulated sugar in large bowl with electric mixer on medium speed 5 minutes or until light and fluffy. Beat in eggs, 1 at a time. Mix in sour cream, milk, food colour and vanilla. Gradually beat in flour mixture on low speed until just blended. Do not overbeat. Spoon batter into 30 paper-lined muffin cups, filling each cup 2/3 full.