First, find some pretty glasses, preferably one portion sized, more vertical than round. The layers look prettier than way.
For the rhubarb layer:
Trim and cut some rhubarb in 1 inch pieces, toss the pieces into a pot with some sugar (about half a cup of sugar per pound of rhubarb), and allow them to macerate for a half hour. I think I used about 4 or 5 stalks. It doesn't really matter how much rhubarb you make because you can always use the stewed rhubarb for other desserts. I even froze some.
Then stew over medium low heat until the rhubarb breaks down into a compote, about 20-30 minutes. Taste to see if you need more sugar. Allow to cool then spoon into the bottom third of each of your glasses. Refrigerate at least 4 hours.
For the panna cotta:
2 tablespoons water
1-1/4 teaspoons unflavored gelatin
2 cups whipping cream
1-1/4 cups whole-milk yogurt
1 teaspoon rosewater
1/2 cup sugar
Pour 2 tablespoons water into small bowl. Sprinkle gelatin over water. Let stand until softened, about 15 minutes. Whisk 1 cup cream, yogurt, and rosewater in large bowl to blend. Heat remaining 1 cup cream and 1/2 cup sugar in small saucepan over medium heat, stirring until sugar dissolves and cream comes to simmer. Remove from heat. Add gelatin mixture, stirring to dissolve gelatin. Mix hot cream-gelatin mixture into yogurt mixture in bowl. When the panna cotta starts to cool, put it in the refrigerator and watch it. When it starts to thicken, pour it on top of the rhubarb to fill the next third of the glass (or slightly more if you like panna cotta). Refrigerate desserts uncovered until cold, then cover and refrigerate overnight.
For the praline:
Toast and finely chop a handful of pistachios. Sprinkle them on top of the panna cotta. Then combine a cup of sugar in a pan with a splash of water and a squeeze of lemon and place over medium high heat to caramelize, swirling the pan as needed to caramelize the sugar evenly. When the sugar has turned a dark caramel color, turn off the heat and add a tiny splash of water. Pour the caramel in a thin, even layer over the pistachios, working quickly as it will harden as soon as it hits the cold custard. Don't make this layer too thick or you'll need a hammer to break through!
An hour before you plan to serve the dessert, dice up a few strawberries and toss with sugar to taste and, if desired, a splash of kirsch. Allow the strawberries to macerate for an hour. To serve, spoon macerated strawberries over the praline layer. (This made enough for about 6 glasses.)