Prep: Preheat your oven to 400°F (200°C). Line a large rimmed baking sheet with parchment paper. (If using foil, grease it heavily with non-stick spray).

Arrange Crackers: Lay the Ritz crackers out in a single layer on the baking sheet. Make sure they are touching side-by-side with no large gaps.

Make Toffee: In a medium saucepan over medium heat, combine the butter and brown sugar. Bring to a boil. Once it is fully boiling (large rolling bubbles), let it boil for exactly 3 minutes. Do not stir constantly, just give the pan a gentle swirl occasionally.

Pour & Bake: Immediately pour the hot caramel mixture over the crackers. Use a spatula to quickly spread it evenly to the edges. Bake in the preheated oven for 5 to 6 minutes. The caramel will be bubbling vigorously.

Melt Chocolate: Remove pan from oven. Immediately sprinkle the chocolate chips evenly over the hot toffee. Let sit for 2–3 minutes to soften.

Spread: Use an offset spatula or knife to spread the melted chocolate into a smooth layer over the crackers. Add toppings (sea salt/sprinkles) now while the chocolate is wet.

Cool: Let cool at room temperature for 30 minutes, then transfer to the fridge or freezer for at least 30 minutes until the chocolate and toffee are completely hard.

Serve: Lift the parchment paper out of the pan and break the bark into pieces (or cut along the cracker lines).