Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper.
Arrange saltine crackers in a single layer on the prepared baking sheet.
In a saucepan, melt the butter and brown sugar over medium heat, stirring constantly until smooth and bubbly.
Remove the saucepan from heat and stir in the vanilla extract.
Pour the butter-sugar mixture evenly over the saltine crackers, spreading it with a spatula to cover completely.
Bake in the preheated oven for about 5-7 minutes, until the toffee topping is bubbling.
Remove the baking sheet from the oven and sprinkle chocolate chips over the hot toffee. Let them sit for a few minutes to soften, then spread the melted chocolate evenly over the toffee layer.
If desired, sprinkle chopped nuts and sea salt flakes over the melted chocolate for extra flavor and texture.
Allow the Christmas Crack to cool completely at room temperature or in the refrigerator until the chocolate has set.
Once set, break the candy into pieces and serve. Enjoy the delicious holiday treat!