Rhubarb Bourbon Brown Butter Tart with Almond Crust
I’ve been eyeing Deb’s Cherry Brown Butter Bars (adapted from Bon Appetit’s Raspberry Brown Butter Tart) for what seems like forever. It’s actually only been since June 29, 2009. But four years without tasting buttery crust against fruit-studded brown butter custard might as well be eternity.
Yesterday, with a refrigerator full of rhubarb, I decided that enough was enough. I added sugared slices of my favorite “fruit,” a vanilla bean, and a splash of bourbon to the heaven-sent filling, and threw the whole thing in an almond press-in crust. It’s my new favorite dessert.
Whoever coined the term “easy as pie” obviously never made one from scratch. Pie dough is finicky, and challenging to get just right. (You should still make pie, though.) This tart dough, on the other hand, is stupid simple. Everything gets whizzed in the food processor until it begins to clump together, and the crumbs get dumped into the awaiting tart pan. It takes a bit of patience to press the edges and bottom into a smooth, even layer, but after a brief stint in the freezer, the crust holds itself up in the heat of the oven without needing the help of pesky pie weights. It ends up tasting like a buttery shortbread cookie kissed with salt and toasted almonds.
The filling is just as much of a breeze. The magic happens when you cook the butter with a vanilla bean until the milk solids caramelize and smell like baking cookies. This glorious golden substance gets whizzed, in the unwashed food processor bowl, into a custard of eggs, sugar and flour, then doused with a shot of bourbon. The custard is poured over the awaiting rhubarb-filled crust, and baked until puffed and golden.
The rhubarb turns meltingly tender as the tart bakes, and it retains its puckery tartness in the final dessert, which is, to my taste, perfectly sweetened. The bourbon adds a bit of subtle complexity to the custard; I can definitely sense its presence, but it melts into the background of nutty butter and floral vanilla. The crust is so tender, it crumbles under the merest pressure of a fork, though it holds together sturdily enough to transport slices from pan to plate. It is buttery and crisp against the creamy filling – ultra satisfying.
You could top this with a plume of softly whipped cream, flavored with vanilla and a splash of bourbon if you like, but the tart is more than adequate on its own. It’s an easy dessert to whip up for company who will think you spent an eternity making it. Little will they know.
Rhubarb, Bourbon, and Brown Butter Custard Tart with Almond Crust
I do love the bourbon here, but the tart will still rock if you wish to omit it entirely or substitute brandy or another type of whiskey in its place. Be sure to trim away any rhubarb leaves as they are toxic. If you don’t have a food processor, you can easily make this by hand by chopping the almonds very finely, rubbing the buttery dough with your fingertips, and using a whisk and bowl to make the filling. I baked this in my favorite 8-inch tart pan which just barely held all of the filling; a 9-inch pan will work perfectly, too. This tart holds its own, but feel free to serve it with lightly sweetened whipped cream flavored with a splash of vanilla and bourbon.
1/4 cup powdered sugar, plus extra for sprinkling on the finished tart
1/4 teaspoon fine sea salt
3/4 cup all-purpose flour
6 tablespoons cold, unsalted butter, cut into 1/2″ chunks
Rhubarb, Bourbon and Brown Butter Filling:
12 ounces rhubarb, trimmed, sliced on the diagonal 1/2″ thick (3 cups)
2 tablespoons organic cane sugar, plus 1/2 cup for the custard
8 tablespoons unsalted butter
1 vanilla bean, split lengthwise and scraped
1/4 cup all-purpose flour
1/4 teaspoon fine sea salt
2 tablespoons bourbon whiskey
Make the crust:
Position a rack in the lower third of the oven and preheat to 350º.
In the bowl of a food processor, process the almonds, powdered sugar, salt and flour until the almonds are finely ground. Add the butter, and pulse until the mixture just begins to clump together. Dump the crumbs into an 8 or 9-inch tart pan with a removable bottom. Don’t bother washing the food processor bowl. Press the dough into the sides of the pan first, then the bottom, taking time to make square corners, a neat top, and an even thickness. (If the dough becomes soft or sticky, put the whole pan in the refrigerator for 5-10 minutes to firm it up again.) Prick the bottom of the crust all over with a fork. Freeze the crust until firm, 15 minutes, or wrap for longer storage.
Place the tart pan on a rimmed baking sheet for easy maneuvering, and bake the unlined crust until it is pale golden, 15-20 minutes, rotating after 10 minutes for even browning.
Meanwhile, make the filling:
Toss the sliced rhubarb with 2 tablespoons of the sugar in a medium bowl and set aside to macerate while you finish baking the crust and making the custard.
Place the butter and vanilla pod and scrapings in a medium, heavy-bottomed saucepan and cook over medium heat, swirling occasionally. After about 5-10 minutes, the butter will foam up, turn golden and smell nutty, with brown flecks mingling with black vanilla bean seeds. At this point, remove the pan from the heat. Remove the vanilla bean (you can rinse and dry it and stick it in a jar of sugar, or use it to make vanilla extract). Pour the butter into a heatproof measuring cup to stop the cooking, and let cool 5 minutes.
In the bowl of the food processor, pulse together the remaining 1/2 cup of sugar, the flour and salt to combine. Add the eggs, and process until combined. With the motor running, pour in the brown butter, including the brown flecks and vanilla seeds, then the bourbon.
Assemble, bake, and eat the tart:
Scrape the rhubarb and any juices into the hot, par-baked tart shell in an even layer. Carefully pour the custard over the rhubarb, filling the shell to the brim.
Bake the tart until the filling is puffed and browned, 30-45 minutes, rotating the tart halfway through for even baking. Remove the pan from the oven and let the tart cool until warm. Set the tart on an inverted bowl or ramekin, and ease off the ring. Sprinkle the tart with powdered sugar, cut it into wedges, and serve warm or at room temperature.
The tart keeps well in the refrigerator for several days; re-warm slices in an oven or toaster oven for best results.