Mix 2 cups sugar, 1/4 cup light corn syrup and 1/2 cup water in a small saucepan. Bring to a boil over medium-high heat, stirring just until the sugar dissolves. Cook, swirling the pan (do not stir), until the mixture is light amber and a candy thermometer registers 320 degrees, 8 to 10 minutes. Remove from the heat; slowly whisk in 1/2 cup heavy cream, then 2 tablespoons unsalted butter, 1 teaspoon vanilla extract and a pinch of salt. Return to low heat and whisk until smooth. Let cool until the caramel is thick enough to coat a spoon. Insert sticks into the stem ends of 6 apples and dip the apples into the caramel, letting the excess drip off. Roll in toppings if desired, then let cool on a parchment-lined baking sheet coated with cooking spray.