1. Heat your oven to 350°F.
2. Line an 18×12-inch rimmed baking sheet with parchment paper, letting it hang over the sides so you can lift the bark out later.
3. That overhang saves mess and is very handy to pick it up out of the baking sheet.
4. Cover the bottom of the pan with 40 to 50 saltines or pretzel sticks, keeping them snug with minimal gaps.
5. In a medium saucepan, melt 1 cup salted butter over medium heat.
6. Add 1 cup brown sugar, stir until melted and smooth, then stop stirring completely once it reaches a steady boil.
7. Let the butter and brown sugar boil for 3 full minutes, untouched. This is important for the toffee to set properly, so don’t rush it.
8. Carefully pour the hot toffee over the crackers or pretzels.
9. Use a spatula to gently spread the toffee mixture over the base, if needed, so everything gets coated.
10. Bake for 5 to 8 minutes, watching closely. Remove the pan once the toffee is bubbling all over. 
11. Immediately sprinkle 2¼ to 2½ cups semi-sweet chocolate chips evenly over the hot toffee.
12. Let them sit for 2 to 3 minutes until glossy and soft, then gently spread into an even layer.
13. If the chocolate isn’t fully melted, slide the pan back into the oven for 1 minute, no longer.
14. Optional swirl: Melt white and semi-sweet chocolate separately and drizzle both over the hot toffee, then swirl with a toothpick in fun and beautiful patterns.
15. While the chocolate is still warm, scatter your toppings of choice over the top. Lightly press them into the chocolate with the back of a spoon so they stick.
16. Chill in the refrigerator for about 60 minutes, or until completely firm.
17. Lift out using the parchment, break into bite-sized pieces, and try not to snack too much before storing.

Storage

1. Store Christmas Crack Toffee Bark in an airtight container in the refrigerator for up to one week. It also freezes well if you hide it from yourself.