In a large mixing bowl, combine 1 cup of glutinous rice flour, 2 tablespoons of cornstarch, 2 tablespoons of cocoa powder, and 1/4 cup of white sugar. Slowly whisk in 1/2 cup of corn oil and 1 cup of milk until the mixture is smooth and free of lumps.

Pour the combined batter into a fine sieve placed over a medium pot to remove any lumps.

Place the pot over low heat, stirring continuously with a spatula for 10-15 minutes until the batter thickens.

Carefully transfer the hot batter onto a surface sprinkled with cornstarch to cool for about 5 minutes, then stretch and pull the dough gently.

Divide the stretchy mochi dough into tablespoon-sized portions and roll each piece into smooth balls.

Crush Oreo cookies into fine crumbs and roll each mochi ball in the Oreo crumbs until fully coated.