For the simple syrup, combine 1 cup water and 1 cup sugar in a saucepan and bring to a simmer. Stir until sugar is dissolved and simmer for one minute. Allow to cool.

Combine 2 tablespoons simple syrup with 1/4 teaspoon blue butterfly powder. Mix until smooth.

In cocktail shaker filled with ice, combine the tequila, triple sec, lime juice and blue butterfly simple syrup. Shake until combined and chilled.

Pour into a margarita glass  and garnish with a lime slice if desired.