Line a baking sheet with aluminum foil. Arrange the saltine crackers in a single layer, covering the entire pan.
In a small saucepan over medium heat, melt the butter and brown sugar together. Stir constantly until the mixture starts to bubble, then let it simmer for about 3 minutes until it thickens slightly.
Carefully pour the caramel mixture over the crackers, spreading it evenly. Bake in a 350°F oven for about 10 minutes, or until it’s bubbly and golden.
Remove the pan from the oven and immediately sprinkle the semi-sweet chocolate chips over the hot caramel layer. Let them sit for a minute or two to soften, then use a spoon to spread the melted chocolate evenly. Drizzle the melted white chocolate over the top and swirl it with a toothpick for a pretty marbled effect.
While the chocolate is still warm, sprinkle on the Robin Eggs, M&Ms, and festive Easter sprinkles. Press them in slightly so they stick as the bark cools.
Pop the tray in the fridge for about an hour. Once the bark is fully set, break it into pieces and enjoy!