1. Preheat the oven to four hundred Fahrenheit. Line a 15×10 inch jelly-roll pan with aluminum foil and parchment paper. Arrange saltine crackers in a single, tight layer across the pan.

2. In a medium saucepan, combine the butter and brown sugar. Bring the mixture to a full, rolling boil over medium-high heat, stirring constantly.

3. Continue to boil the mixture for exactly three minutes.

4. Pour the hot toffee evenly over the cracker layer, ensuring all crackers are covered. Bake for five minutes.

5. Remove the pan from the oven and evenly sprinkle the chocolate chips over the hot toffee. Let sit for five minutes to melt.

6. Use an offset spatula to gently spread the melted chocolate into a smooth, even layer. Sprinkle with optional nuts and flaky sea salt.

7. Allow the toffee to cool completely at room temperature or chill in the refrigerator for at least one hour.

8. Break the finished confection into irregular, bite-sized pieces for serving.