Line an 8×8-inch baking dish with parchment paper.
In a saucepan, combine dark chocolate chips, condensed milk, and butter over low heat until smooth.
Stir in vanilla extract for balance.
Spread the mixture evenly in the pan.
Melt white chocolate, divide into bowls, and tint blue and purple. Drizzle and swirl gently.
Top with edible glitter or star sprinkles.
Refrigerate for at least 2 hours, then cut into squares.
