First, line a 8X8 baking pan with butter paper and keep it aside. Also, measure and keep the vanilla extract and baking soda, ready.
Take a tall heavy bottomed pan. Add the butter, brown sugar, corn syrup, water and salt. Mix well and heat it in medium flame.
Keep stirring continuously until everything is melted, combined together and the mixture starts to boil. If sugar crystals are formed in the sides of the pan, dip a brush in water and brush the sides of the pan clean.
Once the mixture starts to boil, insert the candy thermometer into the mixture and stop stirring. You should not stir or disturb the mixture after this stage. Let the mixture continue to boil until it reaches the soft crack stage. The candy thermometer should read 280 - 285 F temperature. This is the correct temperature for soft crack consistency.
Immediately, remove the pan from the flame and add the vanilla extract and baking soda. Stir well until combined and transfer the mixture quickly to the baking pan. Gently tap the pan to level off the mixture.
While the mixture is still hot, add the chocolate chips evenly on top. Wait for a couple of mins until the choco chips melt.
Use a spatula or back of a spoon to spread the chocolate layer evenly over the top of the toffee layer. Add the M&M’s® Easter Sundae on top of the chocolate layer. Refrigerate until the chocolate is firm. Pull the bark out of the refrigerator and cut into pieces using a sharp knife.
Enjoy or store in an airtight container.