Adjust oven rack to middle position and preheat the oven to 170C/338F. Line two 12-cup cupcake pans with 16 paper liners.

In a medium bowl, whisk together the flour, cocoa powder, baking soda and salt to combine. Set aside.

In a small bowl or a large liquid measuring cup, whisk together the buttermilk, vinegar, vanilla and food coloring. Set aside.

In the bowl of a stand mixer fitted with the paddle attachment (or in a large mixing bowl and an electric hand mixer), beat the butter on medium speed until creamy, about 1 minute. With the mixer running, gradually add in the sugar, then slowly drizzle the oil. Raise the speed to medium-high and continue beating together, scraping down the bowl as necessary, until lightened up in both color and texture; 4 to 5 minutes.

Add the eggs, one at a time, beating well after each addition.

Scrape down the bowl and beater with a spatula, then resume mixing on lowest speed. Add in one-third of the flour mixture and beat until just incorporated. Pour in half of the buttermilk mixture and beat lightly until combined. Repeat with half of the remaining flour mixture, remaining buttermilk mixture, and ending with the remaining flour mixture, scraping down the bowl as necessary. Mix until just combined and a smooth batter forms, being careful not overmix.

With a rubber spatula, give the batter one good, final stir to make sure that everything is well incorporated. Use an ice cream scoop to divide the batter evenly among the 16 cupcake liners, filling them up ¾ of the way.

Bake until the cupcake's center springs back when lightly touched and a toothpick inserted in the center comes out clean or with a few moist crumbs attached, about 20 minutes.

Let cool in the pan for about 5 minutes then transfer to a wire rack to cool completely before frosting.

While the cupcakes bake, make the Whipped Cream Cheese Frosting.

In the bowl of a stand mixer fitted with the whisk attachment (or in a large bowl and an electric handheld mixer), beat the butter until lightened up and creamy; 2 to 3 minutes.

With the mixer running on low speed, gradually add in the confectioners sugar, followed by the salt. Raise the speed to medium-high and whip until lightened in both color and texture; about 5 minutes.

With the mixer still on medium-high speed, add one piece of cream cheese at a time, one after the other, mixing well after each addition so there are no lumps. Continue whipping until light and fluffy, and air pockets have formed.

Beat in the vanilla and sour cream (if using) just until incorporated.

Fill a piping bag fitted with your favorite piping tip with the Whipped Cream Cheese Frosting. To frost, start piping in the center, going around once, then ending with a swift pull.

Top with the chocolate seal stamps (if using), red fondant hearts or sprinkles, if desired.