Coat one side of the orange slice with sugar. Heat a small, cast iron skillet on high. Place the orange slice, sugar-side down, in the skillet and sear for 1-2 minutes until caramelized. Remove from pan and let cool, browned side up.

Combine remaining ingredients in a mixing glass and stir over ice until chilled. Strain into a double rocks glass over one large ice cube. Place the orange slice, caramelized side up, on top of the ice cube.