For the cake: Preheat the oven to 350 degrees. Line 36-48 mini muffin tins with paper cups.
Melt the chocolate in a small bowl in the microwave (about 45 seconds). Let cool.
Mix flour, baking soda and salt in small bowl.
Combine milk and vinegar.
Beat sugar, oil, eggs and vanilla in large mixer bowl on high for 2 minutes.
Beat in melted chocolate and red food coloring.
Beat in flour mixture alternately with milk mixture.
Spoon into prepared muffin cups, filling 2/3 full.
Bake for 13 to 15 minutes or until wooden pick inserted in centers comes out clean. Cool in pan for 10 minutes and then on a wire rack until cooled completely.
To make the frosting: Beat the cream cheese, butter, milk and vanilla in a bowl until light and fluffy.
Gradually beat in powdered sugar.