Cherry Crumb Tart

Instructions

1. Put the sugar in a medium bowl. If you're using the orange zest, sprinkle it over the sugar and work the two ingredients together with your fingers until the sugar is moist and fragrant.
2. Add the flour, salt, and cardamom, if using, and mix everything together by running the ingredients through your fingers. Drop in the butter and squeeze and rub the butter into the mixture until it's sandy. If you press a little streusel together, you'll get lumps, which is just what you want.
3. Drizzle the vanilla over the streusel and toss, squeeze, and rub to distribute. Cover the bowl and chill the streusel until needed; the crumbs are best used cold.
4. You can make the streusel up to 1 week ahead. Pack it into an airtight container and keep it refrigerated.
5. You can make the filling in the food processor, or in the bowl of a stand mixer fitted with the paddle attachment, or in a large bowl with a hand mixer. Beat the butter until it is smooth and creamy, about 3 minutes. Add the sugar and beat for a minute or two more. Add the nut flour and cornstarch and beat until the mixture is smooth once again. Drop in the egg and beat for a minute or so, until it is thoroughly incorporated. Finally, beat in the kirsch or the vanilla. You can use the filling now, but it's best if you can give it at least 1 hour in the refrigerator. The filling can be refrigerated, tightly covered, for up to 3 days.
6. Center a rack in the oven and heat the oven to 350° F. Place the tart pan with the partially baked crust on a baking sheet lined with parchment paper or a silicone baking mat.
7. Using a short offset spatula or the back of a spoon, spread the filling evenly over the crust. Top with the cherries. You should have enough cherries to just about complete cover the filling.
8. Bake the tart for about 45 minutes, or until the filling is lightly colored-it won't be firm-and puckered up around the cherries. If you've used whole cherries, the tart will look tufted.
9. Pull the baking sheet out of the oven and sprinkle the top of the tart with the streusel. It's nice to have a bumpy topping, so pinch the streusel into nubbins as you take it out of the bowl. Gently pat the streusel down.
10. Bake the tart for another 30 to 35 minutes, or until the crumbs are a beautiful golden brown. You don't have to worry about overbaking the filling, so keep the tart in the oven until the top is just the color you want. Transfer the tart to a rack to cool to room temperature.
11. Before serving, dust the tart with confectioners' sugar, if you're using it. Serve with creme fraiche, if you'd like.
12. I think this tart is best served at room temperature the day it's made, but my husband disagrees. As much as he likes it just made, he really likes it after it's spent a night in the refrigerator. He's not wrong about the chill-the tart is very good cold. So if you'd like, you can keep it covered in the fridge for up to 1 day.