Preheat oven to 350°F. Line a 12- or 24-cup muffin tin with paper liners.
In a large bowl, combine the Betty Crocker Black and White cupcake mix, 2 eggs, 3/4 cup water, and 1/4 cup vegetable oil. Beat until smooth and no large lumps remain (about 1–2 minutes by hand or with a mixer).
Divide batter evenly among the liners, filling each about two-thirds full.
Bake at 350°F for 18–23 minutes, or until a toothpick inserted in the center of a cupcake comes out clean. Let cupcakes cool in the pan 5–10 minutes, then transfer to a wire rack to cool completely.
When cupcakes are cool and you are close to serving, make the frosting: empty the frosting pouch into a bowl, add 1/2 cup softened butter and 2 teaspoons water, and beat until smooth and spreadable (about 1–2 minutes).
Fit a piping bag with a decorating tip (for example a Wilton 1M), fill the bag with frosting, and pipe a swirl on each cooled cupcake.
For the Mickey ears, break each Oreo into two equal cookie halves. Place two Oreo halves at the top of each frosted cupcake to form ears (two halves per cupcake).
Sprinkle with the sprinkles as desired and serve.