Preheat oven to 300°.
Combine first 5 ingredients in a bowl; stir well with a whisk. Place egg yolks in a medium bowl; stir with a whisk until smooth. Gradually whisk milk mixture into egg yolks. Stir in liqueur. Divide mixture evenly among 5 (4-ounce) ramekins or custard cups. Place ramekins in a 13 x 9- inch baking pan; add hot water to pan to a depth of 1 inch.
Bake at 300° for 1 hour or until center barely moves when ramekin is touched. Remove ramekins from pan, and cool completely on a wire rack. Cover ramekins, and chill at least 4 hours or overnight.
Place sugar and water in a small, heavy saucepan over medium-high heat; cook 9 to 10 minutes or until golden. Immediately pour caramelized sugar evenly over cold custards to form a paper thin layer on tops of custards. Serve immediately.