Preheat oven to 400˚F / 205˚C. Line an 18" x 13" sheet pan with silpat, parchment paper or aluminum foil.
Place saltine crackers on the sheet pan in an even layer, leaving about 1 inch of space around the edges of the pan.
Combine the butter, brown sugar, and half of the bourbon in a medium saucepan over medium heat. Bring to a boil, and boil for 3-4 minutes, whisking occasionally.
Remove from heat and carefully whisk in the other half of the bourbon and the vanilla extract (it will bubble up a bit when you add in the bourbon, so be careful!). Pour the caramel evenly over the bed of saltine crackers and use a nonstick spatula to smooth it out. Make sure it covers all of the saltines.
Place sheet pan in the oven for 5 minutes. Remove from the oven and sprinkle chocolate chips on top in an even layer, then return to the oven for 2-3 minutes to fully melt the chocolate chips.
Use a spatula to spread the chocolate into an even layer, then sprinkle chopped pecans and flaky salt.
Let it cool completely so the chocolate and toffee can set (about 1-2 hours), then crack it up into bite-sized pieces and enjoy!
