Makes one parfait.
1 cup plain low-fat yogurt
1 tsp agave nectar or honey
Zest of 1 lemon
1/4 tsp pure vanilla extract
Pinch of kosher salt
4 large whole blackberries
10 lemon wafer-type cookies
In a mixing bowl, combine the yogurt, agave or honey, lemon zest, vanilla extract and salt. Whisk everything together until smooth. Remove half of the mixture to another bowl, and in that bowl, crush up one of the blackberries and stir it into the yogurt. Set both bowls aside.
On a board or plate, crush the lemon cookies roughly with a rolling pin or potato masher.
Assemble your parfait: In a small glass or glass jar, place the remaining 3 whole blackberries. Spoon on the blackberry-yogurt mixture. Sprinkle half of the cookie crumbs on the blackberry yogurt. Add the remaining lemon yogurt, and a final layer of cookie crumbs on top.
Parfaits can be assembled a few hours ahead, though the longer they sit, the more the layers will settle. If you're making and serving these at home, you can set up the bottom layers of yogurt and cookie crumbs, and finish assembly of the top layer right before serving. Serve cold.