Preheat the oven to 400F degrees.
Line a 10x15 inch pan with aluminum foil and lightly grease.
Place the saltine crackers on the cookie sheet to cover the entire pan in 1 layer of crackers.
Melt together the butter and sugar in a medium saucepan over medium heat.
Once the butter is melted, bring to a boil for 3 minutes while stirring constantly.
Carefully pour the mixture over the crackers. Spread it overtop so that all of the crackers are covered.
Bake in the oven for 5 minutes. Remove from the oven and cool for 5 minutes.
Add the chocolate to a medium heatproof bowl. Microwave on medium power for 1-minute bursts, stirring between each. When the chocolate is almost melted, stir until smooth.
Spoon the chocolate over the crackers, and spread it smooth to completely cover the pan. Decorate with sprinkles.
Let the toffee harden until the chocolate is set. Either at room temperature or in the fridge.
Once completely hardened, remove from the pan peel the aluminum foil off. Break/"crack" it into pieces.
Store in an airtight container at room temperature for up to 5 days, or in the fridge for 10 days.