Melt the butter over high heat. Once the water begins to evaporate, begin to stir to avoid browning. Add the milk solids. Continue stirring. Once the butter browns, pour through a cone filter into a heatproof container to separate the brown butter solids from the clarified butter. Cool to room temperature.
Add the butter solids to the bourbon. Stir to incorporate. Cover and place in the freezer for 6 hours or until the solids separate. Strain off the frozen solids and store in the refrigerator.
In a mixing glass, combine 2 ounces butter-infused bourbon, maraschino liqueur and bitters. Stir over ice. Strain over fresh ice into a rocks glass. Express an orange twist over the glass and drop it into the glass.