Preheat your oven to 350 degrees and line a cupcake tin with 10 liners (alternatively, spray your tin with non-stick baking spray).

In a medium-sized bowl, combine the flour, cocoa powders, baking powder, baking soda and salt. Whisk to combine.

In a separate bowl, combine the oil, espresso powder (if using), white sugar, brown sugar, eggs, vanilla, sour cream and milk. Whisk to combine. Pour over dry ingredients and mix until combined.

Turn out onto a cooling rack and cool completely before frosting.

To make the frosting, beat the softened butter on high speed for 4-5 minutes or until light and fluffy. Slowly beat in powdered sugar and salt until well mixed. Add in vanilla and 1-2 tablespoons of milk until consistency is smooth and spreadable.

To assemble cupcakes, spread frosting over top of each cupcake, reserving 2-3 tablespoons to make the eyes.

Using short bursts of the microwave, melt the mini chocolate chips, reserving 20 of them for the eyes. Transfer the melted chocolate to either a piping bag or a plastic baggie.

Snip the corner of the piping bag (or baggie) and pipe spider legs across the top of the frosting (see picture above). Top with one half of an oreo and repeat.

Transfer remaining buttercream to another piping bag (or baggie), snip the corner and pipe eyes onto the oreo cookie halves. Top with mini chocolate chips.

Cupcakes may be served immediately but will keep in an airtight container for a couple of days. Note that the oreos will soften in texture if they are stored.