Preheat your oven to 400°F (200°C) and line a baking sheet with parchment paper.
Arrange saltine crackers in a single layer on the sheet.
In a saucepan, melt the butter and brown sugar over medium heat, stirring continuously.
Once it boils, let it boil for 3 minutes without stirring.
Pour the toffee mixture over the saltine crackers, spreading it evenly.
Bake for 5-7 minutes until bubbly.
Remove from the oven and sprinkle chocolate chips on top.
Let the chocolate sit for a few minutes, then spread it evenly.
Top with nuts and sea salt, if desired.
Cool completely before breaking into pieces.