Set oven to 350 °F.
Line baking sheet with parchment paper, foil, or silicon liner. If possible, line to/over the edges.
Line up graham crackers over liner, aiming to fill the surface. To catch all the delicious toffee, you may consider breaking some of the crackers to fill the sides.
In saucepan over low heat, melt vegan butter, stirring regularly.
Once melted, add brown sugar, stirring regularly.
At first the butter and sugar will be separated but with stirring and heat, they will form together. Turn up heat slightly to medium low, stirring constantly. Bring to boil and then stir for another 15-20 seconds ONLY.
Pour toffee over graham crackers. Even out with a spatula or spoon to cover crackers.
Bake for about 5 minutes, until toffee is bubbling across entire surface.
Sprinkle with chocolate chips. If you prefer melted chocolate, use a spatula or spoon to melt and spread. It may take a minute at first but the chips will melt.
Sprinkle nuts (optional). Press down slightly for a better chance of nuts sticking/staying in place.
Sprinkle sea salt (optional).
Let cool completely. To speed up cooling, place in refrigerator for an hour.
Break into pieces and enjoy.