Preheat your oven to the temperature specified on your cake mix box and grease your cake pan to prevent sticking.
Mix the vanilla cake batter according to the package instructions using your whisk or mixer until smooth and slightly bubbly—this helps the batter relax and bake evenly.
Pour the batter into your prepared cake pan and smooth the top with a spatula for an even surface.
Bake the cake until the edges are golden and a toothpick inserted in the center comes out clean—usually about 25-30 minutes. Let it cool in the pan for 10 minutes, then transfer to a wire rack to cool completely.
Once cooled, use a straw or skewer to poke holes all over the surface of the cake, spacing them evenly. This creates channels for the milk to soak in.
Crush the Oreos into small, crumbly pieces—this can be done by placing them in a plastic bag and gently smashing with a rolling pin or using a food processor.
Sprinkle the crushed Oreos generously over the surface and into the holes of the cake, pressing gently to embed them into the batter.
Pour sweetened milk over the cake, making sure it soaks into the holes and helps the cake become moist and flavorful.
Let the cake sit for at least 2 hours or overnight in the refrigerator—this allows all the flavors to meld and the cake to become cuddly and rich.
Serve slices with extra Oreo crumbs if desired—this dish is all about a messy, indulgent experience.
