cured rhubarb

1. Trim the rhubarb so it fits lengthwise in a 9" x 13" baking dish. Using a paring knife (a vegetable peeler would remove too much), beginning at one end of each stalk, pull off the strings and any tough peel running the length of the rhubarb; if any stalks are very young and green and don't trim easily, they can be left unpeeled. (don't forget this part and decide to do it after the rhubarb has been soaking in the sugar for 4 hours. It's a sticky mess.)
2. Arrange the rhubarb in the baking dish. Sprinkle with the sugar and drizzle the grenadine over the top. Cover with plastic wrap and refrigerate for 24 hours, turning and tossing the rhubarb every 8 hours to coat it evenly. (The sugar will pull out the moisture in the rhubarb as it sits.)
3. Drain the rhubarb on paper towels; discard the liquid in the pan.

pâte sucrée

1. Place the all-purpose flour in a medium bowl. Sift the 1/4 cup + 2.5 tbsp powdered sugar and almond flour into the bowl; break up any lumps of almond flour remaining in the sieve, add them to the bowl, and whisk to combine.
2. Place the butter in the bowl of a stand mixer fitted with the paddle attachment and cream on medium-low speed, warming the bowl as needed, until the butter is the consistency of mayonnaise and holds a peak when the paddle is lifted. Sift in the remaining 3/4 cup + 1 tbsp powdered sugar and the salt and pulse to begin incorporating the sugar, then increase the speed to medium-low and mix for about 1 minute, until the mixture is fluffy. Scrape down the sides and bottom of the bow. Scrape the seeds from the vanilla bean (or add the extract), add them to the butter mixture, and mix on low speed for about 30 seconds to distribute the seeds evenly.
3. Add the dry ingredients in 2 additions, mixing for 15 to 30 seconds after each, or until just combined. Scrape the bottom of the bowl to incorporate any dry ingredients that have settled there. Add the egg and mix on low speed until just combined, 15 to 30 seconds.
4. Transfer the dough to the work surface. Use the heel of your hand to smear the dough and work it together. Divide the dough in half and form each half into a 4"x6" rectangle, about 3/4" thick (but I left it in one piece and had no issues).
5. Wrap each piece in plastic wrap. Refrigerate until firm, about 2 hours, but preferably overnight. The dough can be refrigerated for up to 2 days or frozen for up to a month.

tart shell

1. Preheat the oven to 350 F. Spray the quarter sheet pan with nonstick spray. Line the bottom with parchment paper.
2. Roll out the dough to a 12" x 16" rectangle, just under 1/8" thick. Line the sheet pan, and then line the shell with parchment paper. Fill the shell will raw rice (I used beans, but Keller advises against beans because they will leave an imprint in the dough, unlike rice).
3. Bake for 15 minutes, then rotate the pan and bake for another 15- 20 minutes, until the dough is set and no longer sticks to the parchment paper.
4. Remove the parchment and rice (or beans, and store for future use), return the pan to the oven, and bake another 15 minutes, or until the dough is golden brown. Set the pan on a cooling rack and cool completely.

toasted almond streusel

1. Combine the all-purpose flour, almond flour, sugar, and salt in a bowl and whisk to break up any lumps.
2. Add the butter and toss to coat the pieces. Work the mixture with your fingertips, breaking the butter into pieces no larger than 1/8" and combining it with the flour mixture. Do not overwork the mixture or allow the butter to become soft; if it does, place the bowl in the refrigerator to harden the butter before continuing.
3. Transfer the streusel to a covered container or resealable plastic bag. Refrigerate for at least 2 hours, or up to 2 days, or freeze for up to 1 month.
4. Preheat the oven to 325 F.
5. Spread the cold streusel in an even layer on a sheet pan. Bake for about 12 minutes, turning the streusel with a metal spatula every 4 minutes, until it is golden brown and dry. Place the pan on a cooling rack and let cool completely. **Note: watch very carefully if your oven is finicky. The streusel can brown/ burn very quickly.
6. Pour the streusel into a food processor and pulse to the consistency of brown sugar (I skipped this part in favor of a crunchier texture and to avoid dirtying the food processor). The streusel can be stored in a covered container for up to 2 days.

brown butter filling

1. Whisk together the almond flour and all-purpose flour in a medium bowl, breaking up any lumps in the almond flour.
2. Combine the eggs, sugar, and salt in the bowl of a stand mixer fitted with the whisk attachment and mix on medium speed for about 2 minutes, until thickened. With the mixer running on medium-low, slowly add the milk and cream. Add the dry ingredients and mix on medium- low for a few seconds, until combined. With the mixer running, slowly add the brown butter and mix to combine. Transfer the filling to the pastry bag (I found a spoon worked fine).
3. Pipe (or spoon) enough of the filling into the crust to cover the bottom with 1/4" thick layer, and spread it evenly with a small offset spatula. Arrange the rhubarb rounded side up on top of the filling, running lengthwise in the pan (if any pieces are shorter than the pan, patch them with a piece cut from another stalk). Pipe (or spoon) the filling around the stalks, filling in any gaps, then spread any remaining filling over the top of the rhubarb (it may not be completely covered).
4. Bake for 40 minutes. Rotate the pan, reduce the oven temperature to 325 F, and bake for another 10 to 15 minutes, until the filling is set and golden. Set the pan on a cooling rack and cool completely.
5. To serve: lift the tart out of the pan with a large spatula and trim the edges of the crust (alternatively: cut into 12 pieces and remove pieces from pan individually). Cut into 12 pieces and garnish each piece with some streusel topping. Dust the tops lightly with powdered sugar.