Ingredients

Streusel:

½ cup brown sugar

2 tbsp. flour

1 tsp. cinnamon

2 tbsp. butter, cold

Pinch of salt

Dough and kuchen:

2¼ tsp., or 1 package, active dry yeast, or 2 tsp. instant yeast

¼ c. warm water, approximately 110 degrees

2 c. plus 2 tbsp. all-purpose flour, divided

2/3 c. granulated sugar, plus a pinch, divided

1 tsp. salt

½ c. whole milk Greek-style yogurt

1 large egg, at room temperature

Finely grated zest of 1 small lemon

1 tsp. vanilla extract

1¼ sticks (10 tbsp.) unsalted butter, room temperature, divided

6 medium Italian prune plums, stemmed and pitted

Directions

Streusel:

Place streusel ingredients in a small bowl and combine them by rubbing the flour and butter together with your fingertips or using a pastry blender. The mixture should resemble coarse crumbs. Refrigerate until needed.

Dough:

Stir together warm water, pinch of sugar and yeast in a large mixer bowl. Let rest for five to 10 minutes, or until foamy. 

To this mixture, add two cups flour, 2/3-cup sugar, salt, yogurt, egg, lemon zest and vanilla. Fit dough hook on mixer and mix contents of bowl together at medium low speed for one minute. Beat in eight tablespoons of butter, one tablespoon at a time, until each one is incorporated before adding the next. Continue to beat dough at medium speed for five minutes or until smooth and shiny. Dough will be more like a thick batter than a bread dough.

Using a rubber spatula, transfer dough to a glass bowl, sprinkle top of dough with remaining 2 tbsp. of flour, and cover top of bowl tightly with plastic wrap; refrigerate overnight. Remove dough from refrigerator 45 minutes before continuing.

Gently fold in the flour you had sprinkled over the top of the dough the night before; set aside. Lightly butter a 9-inch fluted tart pan with a removable bottom and 2-inch-high sides, or a 9-inch spring form pan. Turn dough out into center of your buttered pan and, using a rubber spatula, smooth it evenly from the center to the sides.

Open and flatten pitted plums, leaving them attached in the center. Using a serrated or very sharp paring knife, cut four to five deep slits on each half, leaving the wedges attached at the top. Fan five of the plums out and place them, skin side down, in concentric circles along the perimeter of the pan. (I accidentally put the plums skin-side-up and it still worked. I actually liked the color contrast!) Fill the center of the pan with the remaining fanned plum. 

Remove streusel from refrigerator and crumble it evenly over top of kuchen. Loosely drape pan with plastic wrap and let kuchen rise for 1 hour and 15 minutes.

Preheat oven to 375 degrees.

Remove plastic wrap and bake kuchen on center oven rack for 40-45 minutes, or until light golden brown and a toothpick inserted in the center comes out clean.

Transfer pan to a cooling rack and cool for five minutes. Then carefully and very gently lift kuchen out of pan. Let cool for at least 30 minutes more on a cooling rack before slicing it into wedges and serving.

Once cooled, this kuchen can be frozen in a jumbo zip-lock freezer bag for a  month. Let thaw lightly covered at room temperature and then reheat for five to seven minutes in a 350-degree oven.

Makes 8-10 servings.