For caramel: In small saucepan, heat granulated sugar, corn syrup, cream and 2 tablespoons butter over medium high heat until sugar melts, whisking continuously. Once sugar begins to boil, stop whisking. Continue heating, without stirring, until it turns light caramel color, 5 to 8 minutes. Remove from heat and whisk in remaining 1 tablespoon butter. Whisk in vodka, vanilla and salt; note that mixture will bubble up. Cool completely.