Preheat the oven to 350°. Line a 12-cup muffin tin with paper or foil liners.
In a medium saucepan, soften the butter with the vegetable oil and water over low heat.
In a large bowl, sift the flour with the sugar, cocoa powder, baking soda and salt. Add the melted butter combination and beat with a handheld mixer at low high-tail till delicate. Add the egg and beat till integrated, then add the buttermilk and vanilla and beat till delicate, scraping the underside and aspect of the bowl. Pour the batter into the lined muffin tins, filling them about three-fourths tubby.
Bake the cupcakes within the center of the oven for approximately 25 minutes, till springy and a toothpick inserted within the center comes out clear. Let the cupcakes frigid a minute, then switch them to a rack to frigid completely. Frost and top the cupcakes as desired. (Confirm recipes for Chocolate Frosting, Marshmallow Frosting or White Buttercream Frosting.)
The unfrosted cupcakes would be wrapped in plastic and kept at room temperature for as much as 2 days or frozen for as much as 1 month.