Preheat your oven to 350°F.

Line a rimmed baking sheet completely with aluminum foil, making sure the edges are covered for easy cleanup. Arrange the crackers in a single, even layer, covering the entire pan. If needed, break a few crackers in half so the surface is fully filled.

In a saucepan, combine the butter and brown sugar. Melt over medium-high heat, stirring occasionally. Continue cooking for about 3 minutes, stirring constantly, until slightly thickened. Immediately pour the hot mixture over the crackers and use a spatula to spread it evenly, working quickly before it sets.

Bake for 15 minutes, until the topping is bubbly and caramelized.

Remove the pan from the oven and place it on a heat-safe surface.

Melt the chocolate until smooth, then spread it evenly over the cracker layer so it covers the surface completely.

Melt the white chocolate separately. Spoon small amounts over the melted chocolate, then use a knife or toothpick to gently swirl the two together.

Sprinkle candies and decorative sprinkles over the top while the chocolate is still soft so they stick.

Refrigerate for about 1 hour, or until fully set. Once firm, break into pieces and serve.