Make Fennel Simple Syrup: Combine ingredients in a 2-qt. saucepan over medium heat until sugar has dissolved, about 2 minutes. Reduce heat to low and cook for 10–15 minutes, until the syrup has thickened. Let cool. Strain, discarding fennel, and store in the refrigerator until ready to use. Leftover syrup will keep, refrigerated, for about 2 weeks.
Make Fall Conniption Punch: Place all ingredients in shaker with ice and shake vigorously.
Pour into glass. Garnish with apple slices and/or cinnamon sticks.