Preheat oven to 400°F and line a baking sheet with foil or parchment paper.

Arrange saltine crackers in a single layer to cover the entire pan.

In a small saucepan, melt butter and brown sugar together, stirring until it starts to bubble. Let it boil for about 3 minutes.

Pour the toffee mixture evenly over the crackers and spread quickly with a spatula.

Bake for 5 minutes, until the toffee is bubbling.

Remove from oven and immediately sprinkle chocolate chips over the top. Let them sit for a minute to melt, then spread evenly.

Add chopped pecans or sprinkles if desired.

Let cool completely, then break into pieces and store in an airtight container.