Preheat oven to 350° F. Line 24 muffin tins with paper liners and set aside.
In large stand mixer or using a hand mixer, whip butter and sugar together until light and fluffy.
Stir in vanilla extract and eggs 1 at a time until combined. Using a rubber spatula, scrape sides of the bowl and mix again.
Slowly stir in all-purpose flour, self rising flour, and milk, alternating back and forth until all ingredients are added to the bowl.
Scrape sides and mix again briefly. Fold in chopped Oreo pieces by hand.
Scoop batter into prepared muffin tins so they are ⅔ full.
Bake 18-22 minutes or until toothpick inserted comes out clean*.
Remove cupcakes from the oven and set aside to cool.
for the frosting-
Using a hand mixer or stand mixer, whip butter and vanilla extract together in a large bowl.
Mix in powdered sugar and then the milk.
Using a rubber spatula, scrape sides of the bowl and whip 1-2 minutes or until light and fluffy.
Fold in crushed Oreos.
Frost cooled cupcakes** and top with a mini Oreo.
Video
Notes
*It's really important to not over bake these so they stay moist. Watch them carefully!** If you plan to pipe the frosting onto your cupcakes like I did, I would recommend doubling the frosting recipe and making sure the Oreo cookies are ground really well so you don't clog your piping bag.