1. Preheat oven to 400 degrees.
2. Whisk together the dry ingredients until they are evenly mixed. Using a standard box or potato grater, grate the frozen butter into the flour mixture and toss lightly with your fingers until it’s thoroughly combined.
3. Pour the milk into the flour mixture and stir quickly with the handle end of a wooden spoon just until the dough comes together. Fold the dough over a few times with your hands until all the ingredients come together. If necessary add a few more spoonfuls of milk to help gather up any stray flour.
4. Pat the dough out on a lightly floured cutting board to form a loose round shape. Cut the round into wedges- like a pie- or any other shape you like and place on a lightly greased baking sheet. Brush pieces with the 2 tablespoons of milk and sprinkle with coarse sugar. Bake for 15 minutes or so, until the tops are golden brown.
1. Put rhubarb into a small pot with the brown sugar. Add a splash of water and bring to a vigorous simmer and continue cooking until the rhubarb softens and thickens, about 10 minutes or so. Remove from the heat and cool then toss together with the strawberries.
2. Now to build your masterpiece! Cut a shortbread in half, spoon some compote over, add the second half, drizzle with more compote and top with a big dollop of whipped cream! Serve and share.