Lay a large piece of parchment or wax paper on the counter. Place a large stockpot over medium heat. Attach a candy thermometer to the side, making sure the tip reaches the bottom of the pot. Add the butter, sugar, and salt.
Bring the sugar mixture to a rolling simmer, stirring the entire time. Continue gently stirring as it boils to keep the butter and sugar from separating, until the temperature reaches between 300-305 degreed F. If the butter and sugar separate, the candy will not have the proper texture. *Be careful; boiling sugar can be dangerous!
Once you reach the desired temperature, immediately turn off the heat. Stir in the vanilla. Then gently pour in the oyster crackers and stir to coat well.
Carefully, pour the crackers out on the parchment paper. Use a spatula to quickly separate the pieces, so they dry individually. **If your candy thermometer is accurate you reached the proper temperature, the candy will dry and harden on its own. It will have a light glossy sheen. If it stays sticky or looks crystalized, your candy thermometer is probably inaccurate. You can fix this by moving the candy onto a parchment paper lined baking sheet. Bake in a single layer at 450 degrees F for 5 minutes.
Once the candy is completely cool, melt the chocolate chips. Either place them in a double-boiler over low heat, stirring until melted, or place in a microwave-safe boil, and nuke in one minute increments, stirring in between until completely melted.
Place the melted chocolate in a plastic zip bag. Snip a tiny piece off one corner to create a piping bag. Then use the bag to drizzle chocolate over all the candy. While the chocolate is still soft, sprinkle the chopped nuts over the top. Let the chocolate dry until hard.
Once the chocolate is hard, break the candy apart and store in an airtight container for up to 2 weeks.
For a less glossy crumbly toffee coating, shoot for a temperature of 290-295 degrees F. For a glossy hard toffee coating shoot for 300-305 degrees F.