Preheat your oven to 400 degrees Fahrenheit. Line a large rimmed baking sheet with parchment paper or a silicone baking mat, ensuring the edges are covered to prevent the toffee from sticking. Arrange the saltine crackers in a single, tight layer on the prepared sheet, breaking some if necessary to fit the gaps.
In a medium saucepan, combine the butter and brown sugar over medium heat. Stir constantly until the butter is melted and the mixture begins to boil. Once it reaches a boil, let it cook for exactly three minutes without stirring. This allows the mixture to caramelize and thicken into a proper toffee consistency. Remove from heat and stir in the alcohol-free vanilla extract.
Carefully pour the hot toffee mixture over the arranged crackers, using a spatula to spread it evenly so every cracker is coated. Place the baking sheet in the oven and bake for 5 to 7 minutes, or until the toffee is bubbling across the entire surface. Watch it closely to ensure it does not burn, as ovens can vary in temperature.
Remove the pan from the oven and immediately sprinkle the chocolate chips over the hot toffee. Let them sit for about two to three minutes until they soften and become glossy. Use an offset spatula to spread the melted chocolate into a smooth, even layer over the toffee surface.
While the chocolate is still wet, sprinkle the chopped pecans evenly over the top, gently pressing them down so they adhere. Allow the pan to cool at room temperature for about 30 minutes, then transfer it to the refrigerator for at least two hours until the chocolate is completely set and firm.
