Place 14 of the blackberries and 2 of the thyme sprigs in a medium bowl. With the back of a wooden spoon, press firmly on the solids until mashed. Mix in the tequila, simple syrup, time juice, and liqueur, then add 1 cup of the ice. Stir to blend well.
Strain into a large glass measuring cup. Mix in the sparkling wine. Divide the remaining ice between 2 tall glasses. Pour the margarita mixture over the ice. Garnish each drink with 1 blackberry and 1 thyme sprig.
Source: Adapted from Epicurious.com via Keri Glassman of The O2 Diet.
image via indulgy.com