How to Make It
In a medium saucepan, combine the rhubarb with the sugar and water and cook over moderate heat, stirring occasionally, until the rhubarb just begins to break down, about 10 minutes. Stir in the strawberries and simmer until softened, about 5 minutes. Transfer the rhubarb mixture to a bowl and let cool for 30 minutes. Gently fold in the raspberries.
Preheat the oven to 425°. Line a baking sheet with parchment paper. In a large bowl, whisk the flour with the sugar, baking powder, poppy seeds and salt. Using a pastry blender, two butter knives or your fingers, cut in the butter until the mixture resembles small peas. Pour in the milk and stir just until a dough forms.
Scrape the dough onto a work surface and form it into a disk. Roll out the disk 3/4 inch thick. Using a 2 1/2-inch round pastry cutter, stamp out 8 shortcakes and transfer them to the prepared baking sheet. Pat the scraps together. Reroll and cut out 2 more shortcakes. Refrigerate until chilled, about 20 minutes.
Brush the tops of the shortcakes with the cream and bake for about 18 minutes, until golden. Transfer the shortcakes to a rack to cool.
Using a serrated knife, split the shortcakes horizontally and arrange the halves in bowls. Spoon the compote onto the bottom halves, dollop with the creme fraîche and close. Serve at once.