Prepare the oven and baking dish: Preheat the oven to 350°F. Line a 9 x 13-inch baking pan with two pieces of overlapping parchment paper, leaving extra length for easy removal. Set aside.
Make the shortbread crust: Using a hand mixer, cream together the butter, sugar, salt, lemon zest, and rosemary. Once the butter mixture is fluffy, add the flour in two parts, mixing until it is all just incorporated and being mindful not to overmix. Use a sturdy wooden spoon to mix in the dry bits from the bottom of the bowl and to scrape the sides.
Using that same spoon, plop dollops of the dough equally spaced into the lined pan. Using your fingers, press the mixture into the lined pan evenly.
Use a fork to delicately poke holes into the crust (but not to the bottom of the pan!).
Bake for 15 minutes or until the edges are just slightly golden. Once baked, remove and set aside while you make your filling. Leave the oven on at 350°F. (The bars will be baked at the same temperature.)
Make the filling: Place the tofu, milk, cornstarch, flaxseed meal, vanilla, and salt in a blender and blend on high for 30 seconds. Scrape the sides down and blend for an additional 10 seconds. Set aside.
Note: Ideally the crust should be done and out the oven before you start making this caramel. You need to focus! To make the caramel, combine the sugar, brown sugar, and maple syrup in a medium pot and place over medium-low heat. Use a wooden spoon to mix well and cook until it begins to gently bubble. Once bubbling, cook and stir for 8 minutes, mixing consistently. (This isn’t the time to step away so stay put.) Once the mixture is thick, turn off the heat and add the coconut oil. Stir to combine.
Blend the set-aside mixture once more for a few seconds and pour directly into the hot sugar mixture. Mix well and fold in the pecans. Once incorporated, pour over the pre-baked shortbread crust. (If using, evenly sprinkle over just a few pinches of flaky salt before baking.)
Bake and chill: Bake for 40-50 minutes in the center of the oven, until the center is only slightly jiggly. Once baked, remove from the oven and let cool. Then cover and chill in the fridge overnight. Slice while cold and enjoy chilled or at room temperature. A dollop of coconut whip definitely doesn't hurt!