Preheat the oven to 350 degrees Fahrenheit.
First, to toast the pecans, place a large saute pan over medium-high heat. Once hot, add in the pecans and cook for around 1-2 minutes, or just until the nuts are fragrant. Shake the pan frequently to ensure the nuts don't burn. Place in a small bowl and set aside.
Line a 9 1/2 inch by 9 1/2 inch baking dish with a piece of tin foil. Make sure the foil goes up the sides of the dish. Lightly grease the foil with vegan butter. Evenly lay across the saltine crackers.
In a large, wide saucepot, add the butter, sugar, milk, and kosher salt. Place the pot over medium-high heat. Use a rubber spatula or a wooden spoon and continuously stir the mixture while bringing it up to a boil.
Boil this mixture, still over medium-high heat, for about 5 minutes until it reaches 285 degrees Fahrenheit. Please use a proper candy thermometer to measure the temperature accurately. Constantly stir this toffee mixture the ENTIRE time it is cooking.
Once the toffee has reached 285 degrees Fahrenheit, quickly and evenly dump it over the saltine crackers. If needed, quickly spread it around using a metal (eating) spoon.
Now, place the dish onto the middle oven rack and bake it for 5 minutes.
Sprinkle the vegan chocolate chips evenly over the toffee crackers and place the dish back into the oven for another 2 minutes.
Use the back of an eating spoon to evenly spread the melted chocolate chips over the toffee crackers.
Quickly sprinkle over the toasted, chopped pecans, as well as an even sprinkling of flaky sea salt. If needed, gently press the larger pieces of pecans down to ensure they are stuck on the chocolate.
Place the baking dish into the refrigerator to chill for 30 minutes or until completely cooled down and firm to the touch.
Lift the tin foil from the pan, peel it out from under the toffee, and lay the toffee on a cutting board. Cut it into whatever size shards you desire.
Store the toffee candy in an airtight container and place it in the refrigerator to prevent them from melting and softening.