Preheat oven to 350 degrees F. Line a large baking sheet with a Silpat baking mat, parchment paper, or aluminum foil. If you are using aluminum foil, spray lightly with nonstick cooking spray. Place saltine crackers in a single layer, touching, on the large baking sheet. Set aside.
In a medium saucepan, melt butter and brown sugar together over medium-high heat. Bring butter and brown sugar mixture to a boil. Boil for 3-4 minutes, stirring constantly. Pour mixture evenly over saltine crackers. Bake for 8 minutes or until topping is bubbling.
Remove the pan from the oven and immediately sprinkle chocolate chips evenly over the top of the crackers. Let the chocolate chips sit for 2 minutes so they have a chance to melt. Spread melted chocolate with a knife or rubber spatula. Sprinkle with candy and sprinkles, if using.
Let the toffee sit for about 2 hours or until the chocolate hardens. You can refrigerate the toffee for an hour, or freeze for 30 minutes. When chocolate is set up, break the toffee into pieces and serve!
Note-You can top the toffee with chopped pecans or almonds. You can also mix up the candy and sprinkle colors for any holiday. The toffee will keep up to 2 weeks in an airtight container in the fridge or in the freezer for up to 2 months.