Line a baking tray or casserole dish with parchment paper and lay down a single layer of the saltine crackers. You may need to break a few to fill in gaps.
Place the butter and brown sugar in a small saucepan and bring to a boil over medium heat. Allow the mixture to melt and blend completely before removing from heat.
Place the crackers in the oven for 10 minutes, until the caramel is completely absorbed and the crackers have taken on a glossy, hard caramel appearance.