Line a baking sheet with parchment paper and have it close at hand.
Melt the vegan butter in a pot, and add the dark brown sugar. Cook the brown sugar and vegan butter on medium-high heat fr around 10 minutes. Continue to stir vigorously for the whole cooking duration.
Using a candy thermometer, check the temperature, once the toffee reaches 280 degrees remove it from the heat.
Carefully pour the toffee onto the baking sheet lined with parchment paper.
Allow the toffee to cool for 5 minutes. Place the toffee in the freezer until set and hard.
Break the toffee into small pieces. Set aside keeping the toffee cold.