In a microwave-safe bowl, combine 2 cups of white chocolate chips and 1 cup of sweetened condensed milk. Heat this mixture in the microwave at medium power for 30 seconds; then stir. Repeat the heating process in 15-second intervals, stirring vigorously each time until smooth, which should take about 1 to 2 minutes in total.

Once melted, add 1 teaspoon of vanilla extract to the mixture. Stir well to incorporate the vanilla evenly.

Fold in the 15 crushed Oreo cookies into the melted chocolate mixture, ensuring the cookie chunks are well distributed.

Line an 8x8-inch baking dish with parchment paper or grease it lightly. Pour the mixture into the prepared dish and smooth the top.

Sprinkle the reserved Oreo cookie pieces over the fudge, gently pressing them down into the mixture.

Refrigerate for at least 2 hours or until firm to the touch.

Once set, lift the fudge out using the parchment paper and slice into squares.