1. Line an 8-inch square baking tin with parchment paper. Use enough parchment paper so that the excess can hang over the sides. Spray or brush with oil.

2. In a small saucepan, melt the cream and butter. Bring to a simmer then take off heat. Set aside.

3. In a larger saucepan, combine the sugars, agave syrup, and water. Mix until the water has fully absorbed into the sugars. Wipe down the sides of the saucepan with a wet pastry brush so there are no sugar crystals clinging on. Clip a candy thermometer onto the side of the saucepan. Make sure the thermometer is not touching the bottom of the pan. The bottom of the pan is in direct contact with the heat and so will be higher in temperature than the caramel inside the pot.

4. Place the saucepan over medium to medium high heat and bring to a boil. Do not stir the contents of the pot. Once the caramel turns transparent and boils rapidly, at around 250 degrees F, turn the heat off and whisk in the melted butter and cream. The contents of the pan will start to bubble and expand. Return the saucepan back over medium to medium high heat and do not stir. When the caramel becomes an amber brown color at 248 degrees F, take off heat. Quickly whisk in the salt, vanilla, andwalnuts then pour into the cake pan. Knock the pan on the counter a few times to remove air bubbles. Sprinkle the top with extra sea salt. Leave, untouched to set for at least 2 hours.

5. Once the caramels have set, lift the parchment flaps to remove from the pan. Grease a knife and cut into small squares or rectangles. Wrap in wax paper or cellophane.