Line an 8×8-inch baking dish with parchment paper.
In a saucepan, melt dark chocolate chips, condensed milk, and butter until smooth.
Stir in vanilla extract.
Spread mixture evenly in pan.
Melt white chocolate and tint with blue and purple gel food coloring.
Drizzle and swirl to create a galaxy pattern.
Sprinkle edible glitter or stars.
Refrigerate for 2 hours, then cut into squares.
