Divide raspberries between 2 deep bowls (2 1/2- to 3-cup size). Add 1 tablespoon raspberry syrup to each and slightly mash fruit. Scoop equal portions of frozen yogurt onto berries.
Pour milk into a Froth Au Lait container and turn motor on. When the froth has formed and the container feels warm to touch, open hatch in lid and pour flan mix powder and remaining 1 tablespoon raspberry syrup into milk. When mixture is well blended or motor turns off, quickly pour and scrape the hot foamy liquid equally over berries and frozen yogurt.
If you don't have a Froth Au Lait, use a blender (foam will be thinner): First pour milk into a glass measuring cup and heat in a microwave oven on full power (100%) until steaming, about 2 minutes. Pour into blender and add flan mix powder and remaining 1 tablespoon raspberry syrup; cover and whirl on high speed until frothy, about 10 seconds. Pour into bowls.