Preheat the oven to 350°F. Line a 9x13 baking sheet with parchment paper or foil. Spray the paper and sides of the pan with non-stick cooking spray (this is an important step).
Add the saltine crackers in a single layer to the baking sheet. Break in half if needed so that crackers fill the whole space.
Melt 1 cup unsalted butter in a small pot over medium-high heat, stirring occasionally.
Add 1 cup brown sugar and stir in. Bring the mixture to a boil and let it cook for 3 minutes, try not to stir during this time (only if you absolutely have to if you think it's going to burn). Set a timer for this step. At the end, the caramel sauce will be bubbly and thick with all the sugar dissolved.
Remove the pot from heat and stir in 1 tsp vanilla extract.
Use a large spatula to pour the caramel sauce overtop of the crackers. Spread it as evenly over each one as you can.
Place the baking sheet in the oven to bake for 5-7 minutes. Remove from oven and let cool 1-2 minutes.
Sprinkle 2 cups chocolate chips over the baking sheet. Place in the oven for 30-60 seconds. No need for the oven to be on, it will still be warm enough to melt the chocolate.
Remove the pan from the oven and use a spatula to spread the chocolate over the entire baking sheet, covering all the cracker edges. Let this cool for 20 minutes then place the baking sheet in the fridge. Let chill for 3-4 hours.
Once chilled, remove the cracker candy carefully from the baking sheet and parchment paper. This may not come off in one piece because the toffee is quite sticky. Place on a cutting board and use a knife to slice into squares or break into pieces. Serve and enjoy!
Recipe Notes:
Storage: Leftovers can be stored in an airtight container on the counter or fridge for up to 1 week. Freezer: I stored mine in the freezer and it defrosted just fine. However, I've read that some people have the cracker base go mushy after freezing. So you might want to test a small batch first to see if it freezes ok for you.