Preheat your oven to 400°F. Line a 10x15-inch baking sheet with aluminum foil and spray it lightly with non-stick cooking spray.

Arrange the gluten-free saltine crackers in a single, even layer on the prepared baking sheet. Set aside while you prepare the toffee.

In a medium saucepan, melt the butter and brown sugar over medium-high heat. Stir constantly as the mixture melts and comes to a boil. Allow it to boil for about 2–3 minutes, stirring occasionally, until it thickens slightly.

Carefully pour the hot toffee mixture over the crackers on the baking sheet, spreading it out evenly with a spatula to coat all the crackers. Bake the toffee-coated crackers in the preheated oven for about 5 minutes, or until the toffee is bubbly and the crackers have a golden color.

Remove the baking sheet from the oven and immediately sprinkle the semi-sweet chocolate chips evenly over the hot toffee. Let the chocolate sit for 2–3 minutes to soften, then use a spatula to gently spread the melted chocolate over the crackers.

Sprinkle the chopped pecans over the melted chocolate. Let the baking sheet cool completely at room temperature. Once cooled, you can add Christmas sprinkles for a festive touch, if desired.

Once the toffee has hardened, break it into bite-sized pieces by hand.