Step 1

Preheat oven to 375°F. Line a baking sheet with aluminum foil and spray with cooking spray. Line with a single layer of crackers arranged side-by-side. A jelly roll pan works best but if your pan is larger just fold up the edges of the foil a bit to create a barrier so the toffee doesn't spread too much when it's added. Set aside.

Step 2

Combine butter and brown sugar in a medium saucepan over medium heat on the stove. Stir with a wooden spoon until the butter has melted and started to combine with the brown sugar. Once the mixture starts to bubble, set a timer for 3 minutes. Let it boil, stirring constantly, until the timer goes off. Remove from heat and stir in the vanilla.

Step 3

Pour the toffee mixture evenly over the saltine crackers, then use a knife to nudge it over any crackers that didn't get covered. It doesn't have to be perfect though because it will continue to spread as the toffee bakes.

Step 4

Place the baking sheet in the oven and bake for 5 minutes until bubbly.

Step 5

Remove the toffee from the oven and immediately sprinkle with the chocolate chips. Let them sit for 2-3 minutes to melt from the residual heat of the pan, then spread with a knife of spatula to create an even coating of chocolate over the top of the toffee. Sprinkle with the chopped pecans, M&M's, or other toppings while the chocolate is still soft.

Step 6

Let the toffee set up until the chocolate has hardened (usually 1-2 hours at room temperature in a cool house, although you can stick it in the fridge or freezer to speed up the process). Break or cut into pieces and store in an airtight container on the counter for 1-2 weeks.