01 -
Preheat the oven to 375°F (190°C). Line an 11x17-inch rimmed baking sheet with parchment paper or nonstick foil.
02 -
Spread the broken pretzels in a mostly single layer over the prepared pan. A few small gaps are fine because the toffee will spread as it bakes.
03 -
Combine the butter and brown sugar in a saucepan over medium heat. Once melted and bubbling, cook for 3 minutes, whisking gently only if needed to keep it smooth.
04 -
Remove the pan from the heat and stir in the vanilla. Pour the hot toffee evenly over the pretzels, then bake for 5 minutes until bubbling across the surface.
05 -
Remove the pan from the oven and immediately sprinkle chocolate chips over the hot toffee. Let them sit for 2-3 minutes, then spread into an even layer.
06 -
Sprinkle with flaky sea salt and pecans if using. Cool completely at room temperature, then refrigerate for 15-20 minutes if needed to firm the chocolate.
07 -
Lift the slab from the pan and break it into pieces. Store airtight in a cool, dry place.