Butter a large baking sheet with 1 teaspoon butter. Sprinkle coconut in a 12-in. circle on the prepared pan. In a large heavy saucepan, combine sugar and corn syrup. Cook over medium heat until a candy thermometer reads 240° (soft-ball stage), stirring constantly. Stir in the macadamia nuts, pecans and remaining butter; cook and stir until the mixture reads 300° (hard-crack stage).
Combine the baking soda, water and vanilla. Remove saucepan from the heat; stir in the baking soda mixture. Quickly pour over the coconut. Cool before breaking into pieces. Store in an airtight container with waxed paper between layers.