1. Preheat the oven to 350°F (175°C) and line a baking sheet with parchment paper or aluminum foil.
2. Arrange saltine crackers in a single layer on the prepared baking sheet to cover the entire surface.
3. In a saucepan over medium heat, melt butter and brown sugar, stirring constantly until the mixture is smooth and bubbly (about 3-5 minutes).
4. Pour the caramel mixture evenly over the saltine crackers, spreading it out with a spatula to ensure full coverage.
5. Place the baking sheet in the oven and bake for 5 minutes until the caramel is bubbling.
6. Remove the baking sheet from the oven and immediately sprinkle chocolate chips over the hot caramel layer.
7. Let the chocolate sit for a couple of minutes to soften, then spread it evenly over the caramel using a spatula.
8. Add optional toppings like chopped nuts, candy pieces, sprinkles, or crushed peppermint while the chocolate is still soft.
9. Allow the chocolate to set by refrigerating the baking sheet for about 30 minutes, or until firm.
10. Once fully chilled, break the Christmas crack into pieces and enjoy.
11. Store leftovers in an airtight container at room temperature or in the refrigerator for up to a week.