Heat oven to 350°F. Line a rimmed baking sheet with parchment or foil.
Arrange graham crackers in a snug single layer on the pan.
Melt butter and brown sugar in a saucepan over medium heat, stirring until smooth.
Bring to a gentle boil and cook 2 minutes, stirring. Remove from heat; stir in vanilla, salt, and cinnamon.
Pour the hot caramel over the crackers and spread evenly. Scatter pecans on top and press lightly.
Bake until the topping is bubbling across the surface, 8–10 minutes.
If using chocolate, sprinkle chips over the hot bark. Let sit 2 minutes, then spread or drizzle.
Cool completely until firm. Refrigerate 15 minutes to speed setting, then break into pieces.