Line two baking sheets with waxed paper; set aside. In a microwave-safe 2-qt. bowl, combine the sugars, water, corn syrup and butter. Microwave, uncovered, on high for 4 minutes; stir until sugar is dissolved. Cook 1-2 minutes longer or until a candy thermometer reads 234° (soft-ball stage), stirring after each minute.
Add pecans and vanilla; stir just until mixture starts to thicken, about 1 minute. Working quickly, drop by rounded tablespoonfuls onto prepared pans. Flatten slightly. Let stand until set. Store in an airtight container.
Editor’s Note: We recommend that you test your candy thermometer before each use by bringing water to a boil; the thermometer should read 212°. Adjust your recipe temperature up or down based on your test.