This is a traditional Spanish dish served at the end of the pilgrimage of St. James. It's a sweet dessert with the classic Spanish flavors of almond, cinnamon and lemon. This tart is great for entertaining, and is a perfect way to end your Easter meal.
Crust: Add the egg and sugar to the bowl of a standing mixer fitted with the paddle attachment. Mix, starting on low speed; gradually raise the speed and beat until frothy. Reduce the speed and add the flour in several additions; mix for another minute. When the dough is slightly dry and still loose, pour it onto a piece of plastic wrap and gather together into a disk. Refrigerate for at least 1 hour, or up to overnight.
Preheat the oven to 300 degrees F. Remove dough from the refrigerator; dust a clean work surface and a rolling pin with flour. Roll the dough into a flat circle by applying even pressure and rotating the dough between passes.Butter the bottom and sides of the tart pan. Use a bench scraper to lift the dough and gently lay it inside the pan. Press the crust into the fluted sides, using excess dough to patch any holes or gaps. Trim any excess dough from the edges. Line the crust with parchment paper or aluminum foil, fill with pie weights or dried beans, and bake for about 20 minutes.
While the crust bakes, prepare the filling: Crack the eggs into a bowl; set aside. Add almonds to the bowl of large food processor; pulse until they resemble a coarse meal. Pour chopped almonds into a bowl, and add 2 cups back to the food processor. (Reserve the remaining chopped almonds for another use.) Grate the lemon peel and part of a cinnamon stick (equivalent to a large pinch) directly into the bowl of the food processor. Finally, add the sugar. Process the mixture to incorporate the ingredients. With the motor running, slowly drizzle in the eggs. The final mixture should be a smooth, evenly mixed batter.
Remove the parbaked tart crust from the oven; the crust should be completely set and slightly golden brown. Remove the pie weights. Pour in the filling, which should come up to just under the top of the tart ring. Carefully carrying the tart pan by the sides (remember, the bottom is removable!), return the tart to the oven and bake for 25 minutes.
While the tart is baking, prepare the rhubarb compote: Slice the stalks of rhubarb on an angle into 2-inch batons. (You will need about 2 cups.) Heat a large, wide sauté pan over medium heat; add the butter. When the butter begins to foam, add the sugar and stir to dissolve. (If using berries instead of rhubarb, adjust sugar to taste.) Once the sugar has dissolved, add the bay leaf and rhubarb and stir to combine. Zest the lemon directly into the pan, and stir again. If the mixture is dry and sandy, add a few tablespoons of water to help the mixture to come to a simmer. Lower the heat and simmer the compote, 10 minutes.
After 10 minutes, remove the rhubarb from the heat. The rhubarb should maintain its shape, but be soft enough to provide no resistance to a cake tester. After 25 minutes, check that the tart is golden and puffed up, and remove from oven. Use a cake tester to verify that the center is set and not runny; then allow to cool completely. Once the tart is cool, remove the tart ring. If you're using a stencil, center it on top of the tart. Place powdered sugar into fine-mesh sieve and evenly dust the tart. Use a knife to carefully remove the stencil. Serve each slice with a spoonful of the rhubarb compote.
Note: Pictures of the cross of St. James are available online and can be printed out or drawn on a standard sheet of paper to make the stencil.