Preheat the oven to 350° and butter and flour a 9-inch round cake pan. In a bowl, whisk the 1 1/4 cups of flour with the granulated sugar, cocoa powder, baking soda and salt. In another bowl, whisk the egg with the 4 tablespoons of melted butter and the oil, vinegar, buttermilk, sour cream, vanilla and red food coloring. Stir the wet ingredients into the dry ingredients until moistened.
Scrape the batter into the prepared cake pan and bake in the center of the oven for about 35 minutes, until a toothpick inserted in the center of the cake comes out clean. Let the cake cool in the pan for 10 minutes, then invert onto a rack and let cool completely.
Line a baking sheet with wax paper. In a bowl, using a handheld electric mixer, beat the butter with the confectioners' sugar, milk and vanilla until smooth. Finely crumble the cooled cake into the bowl and stir until combined.
Using your hands, briefly knead the mixture. Using a 1-tablespoon ice cream scoop, scoop 40 mounds onto the prepared baking sheet. Using your hands, press and roll the mounds into tight balls. Refrigerate until firm.
In a large microwave-safe bowl, heat the white chocolate at high power in 30-second intervals until nearly melted; stir until smooth. Line another baking sheet with wax paper. Dip the cake balls into the melted white chocolate, allowing the excess to drip back into the bowl and transfer to the prepared baking sheet. Let cool until the coating has set. Using a clean, fine-tipped paintbrush, decorate the balls with food coloring to look like eyeballs, or press an M and M onto each cake ball before the coating has set. Serve.