- 1 cup all-purpose flour
- 1 cup whole wheat pastry flour
- 3/4 cup finely chopped walnuts
- 3/4 cup light brown sugar, lightly packed
- 8 tablespoons cold unsalted butter, diced
- 1 egg yolk
- 2 pounds firm, ripe plums, pitted and sliced lengthwise, quarters or sixths
Preheat the oven to 400 degrees. Stir the flours, walnuts and sugar in a large bowl. Cut in the butter and the egg yolk. Mix by hand (or you can use an electric mixer) until crumbly.
Press 1 3/4 to 2 cups of the crumb mixture in an even layer into the bottom of a 9 1/2″ tart pan. Place the plums in, skin side down, in a spiral pattern (begin at the outside, end in the middle).
Sprinkle the remaining crumb mixture over the plums. Bake for 40 minutes, or until the topping is lightly browned. Let cool for 10 minutes on a wire rack. Transfer tart to a flat place or cake stand. You can eat it at room temperature but I recommend chilling it and serving with whipped cream.