Melt In Your Mouth Toffee

unsalted butter (4 sticks)

granulated sugar

light brown sugar, packed

kosher salt, or to taste

to 2 teaspoons vanilla extract

chocolate chips (I used semi-sweet, use milk chocolate if preferred)

to 1+ cup chopped walnuts or pecans, optional and to taste

sea salt flakes, optional for sprinkling

holiday sprinkles, optional