Preheat your oven to 350°F.
Line your muffin tins with liners, add an Oreo cookie to the bottom of each.
In a large bowl, add your cake mix and prepare it to box directions, swapping the water for milk in a 1:1 ratio. Mix until smooth.
Scoop your batter into the liners, filling them about ¾ full.
Bake your cupcakes for about 13-15 minutes on the middle rack of your oven. Cupcakes should be fragrant and just lightly browned on the edges.
Remove from oven, remove cupcakes immediately to a wire cooling rack. Let cool completely to room temperature before frosting.
When cupcakes have cooled, prepare your frosting. Add your butter to the bowl of your stand mixer with paddle attached. Mix on medium for about 2 minutes until butter has become smooth.
Add in the salt and vanilla and mix until incorporated.
Add in the first cup of powdered sugar and mix until a frosting consistency has developed. Repeat with the remaining two cups of powdered sugar.
Add in your 2 tbsp of heavy cream and mix into your frosting on medium-high for about 5 minutes. The frosting should be light and fluffy when it's ready.
If you are planning on piping your frosting, make sure your Oreos are crushed very finely with basically no chunks. Anything bigger than about ⅛ inch will get stuck in your piping tip. I'd recommend using a food processor if you have one. Dump your crushed Oreos into the frosting and fold in with a rubber spatula.
Pipe or use a knife/offset spatula to frost your cupcakes. This frosting should generously frost 12-15 cupcakes, and be almost perfect to frost 20 cupcakes with a smaller to medium amount of frosting.
Store cupcakes in an airtight container for 2-3 days. Enjoy!
