Heat a grill or grill pan to medium-high. Brush the cut side of the peach halves with honey and sprinkle lightly with cinnamon. Grill cut-side down for 2–3 minutes, or until caramelized with distinct grill marks. Let cool slightly.
Rim two glasses by running a lime wedge around the edge, then dip into the cinnamon salt mixture. Fill with fresh ice.
In a cocktail shaker, muddle ½ grilled peach with the agave syrup, lime juice, and basil leaves until the peach is broken down and the basil is fragrant.
Add the tequila, orange liqueur, and a generous scoop of ice. Shake vigorously for 15–20 seconds.
Double strain into the prepared glasses.
Garnish with a grilled peach slice, a lime wheel, and basil flowers.