Preheat and prep. Preheat your oven to 350°F. For my heart shaped cupcakes, I am used a silicone mold which I did not grease because it was new. Note that silicone molds become less non-stick over time, so you might need to grease them lightly with a non-stick pan. If making regular cupcakes with a cupcake liner, place the liners in the muffin tin.
Whisk dry ingredients. Whisk together your dry ingredients - flour, cocoa powder, baking powder, baking soda, and salt. Set aside.
Mix wet ingredients. Add the oil, sugar, and eggs to the bowl of a stand mixer. Mix for 1-2 minutes on medium speed until light and fluffy. Add buttermilk, vanilla, vinegar, coffee, and red food color one at a time on low speed until fully incorporated. You can also use an electric mixer.
Combine and bake. Fold in the dry ingredients into the wet ingredients until just combined. Do not overmix to ensure that the cakes are as tender as possible. Pour the batter into the muffin tins, filling about ¾ of the way. Bake for 20 minutes or until a skewer inserted into the center comes out clean. Cool the cakes on a wire rack.
Make the frosting. While the cakes cool, prepare the Cream Cheese Frosting. Mix cream cheese, butter, sour cream, and vanilla until smooth. Gradually add powdered sugar in batches, beating with the paddle attachment (not whisk!) between each batch. The cream cheese frosting when all the powdered sugar is evenly incorporated and the frosting is stiff and holds its shape. Do not overmix as the batter will liquefy.
Decorate the mini red velvet cakes. Once the mini red velvet cakes are cool, frost with the cream cheese frosting and sprinkles. Lightly smear the sides of the mini cakes with the cream cheese frosting then press into a plate of mini heart shaped sprinkles in various shades of pink to cover the size. Outline the heart of the top of the cake with cream cheese. To pipe the frosting, place some cream cheese into a piping bag and use an open star tip to outline the heart. Feel free to get creative and decorate as you will with your favorite toppings.