Set the oven to 400°F and line a baking dish with parchment paper. The baking dish should be just big enough to fit the cut rhubarb pieces in a single layer.
Wash and dry the rhubarb stalks and discard any leaves, which it should be noted are toxic to humans and animals if consumed. Cut the stalks on the diagonal into 2” sections and place into the lined baking dish, making sure the dish fits the rhubarb snugly. Sprinkle the maple sugar on top of the rhubarb, add the lemon zest and vanilla paste, give everything a good toss and then smooth into one layer. Cover with foil and bake for 15-20 minutes until a liquid syrup has formed. Note that as rhubarb stalks vary widely from the delicate to the hefty, your cooking time may take a little less or a little more than noted depending on the girth of your stalks.
Remove the foil cover and bake for a final 5 minutes, checking that your rhubarb is tender but not disintegrating (although it will still be just as tasty if you have left it too long). Leave on the counter to cool to room temperature.
While the rhubarb is cooling, toast your almond flakes in a pan on medium heat until lightly browned and also let cool.
While I prefer serving this with unsweetened yogurt, if the yogurt you are using is very tangy, or you prefer a sweetened yogurt, add additional maple syrup to sweeten your yogurt before serving.
When ready to serve, place a modest dollop of rich yogurt, about ¼ cup, onto each dish, gently spoon a quarter of the baked rhubarb onto each serving, and drizzle each serving with the syrup from the baking dish. Sprinkle with the toasted almonds, a few sprinkles of maple sugar or splash of maple syrup if desired, and optionally garnish with fresh mint and a few strands of lemon zest if the spirit moves you. Enjoy!