Step 1

Butter an 8 by 8-inch baking dish. Place butter in a large microwave safe bowl (not anything plastic, something micro safe glass or ceramic), heat in microwave until melted.

Step 2

To bowl with butter, add corn syrup, granulated sugar, brown sugar, sweetened condensed milk and salt and whisk mixture very well.

Step 3

Return to microwave and cook mixture on HIGH power for 6 to 7 minutes**.

Step 4

Using hot pads, carefully remove bowl from microwave. Add in vanilla extract and mix well.

Step 5

Pour mixture into prepared baking dish, sprinkle top lightly with Maldon sea salt or fleur de sel if using.

Step 6

Place in refrigerator until set, about 20 - 30 minutes. Cut into rectangular pieces (I cut into rows slightly less than 1/2-inch then cut each row into three) and wrap in cut rectangles of wax paper.