Prep your pan: Lightly grease a 9x13-inch baking dish with butter or non-stick spray and set it aside.

Caramelize the sugar: In a small, heavy-bottomed saucepan, pour in 2 cups of sugar. Cook over low heat, stirring often with a wooden spoon. Continue to cook until the sugar is completely melted and turns a rich amber liquid (about 20 minutes). Keep a close eye on it so it doesn't burn!

Simmer the cream mixture: As the sugar is cooking down, add the remaining 4 cups of sugar and the heavy cream to a large saucepan or Dutch oven (you need a large pot because the mixture will bubble up later!). Simmer this mixture over low heat.

Combine the sugars: Once the sugar in the small pan is fully melted and golden, slowly and carefully pour it into the large saucepan with the simmering cream mixture, stirring continuously. (Caution: The mixture will bubble and steam!)

Cook to Soft-Ball Stage: Bring the heat up to medium. Attach a candy thermometer to the side of the pot and cook, stirring frequently, until the mixture reaches 244°F (soft-ball stage).

Add the mix-ins: Immediately remove the pot from the heat. Carefully stir in the baking soda until completely combined (it will foam slightly). Stir in the butter and vanilla extract until the butter is completely melted and the mixture is smooth.

Let it rest: Leave the candy in the pot and let it rest undisturbed for 20 minutes.

Stir and set: After 20 minutes, add the chopped nuts. Vigorously stir the mixture with a wooden spoon until the glossy sheen disappears and the candy looks matte and opaque.

Cool and serve: Quickly pour and spread the candy into your prepared 9x13 baking dish. Let it cool completely at room temperature for 1 to 2 hours, or overnight. Once firm, cut into small squares and enjoy!