HELLO, POUND CAKE? IT'S ME, STREUSEL

(borrowed and reconfigured from a collection of coffeecakes)
 
makes one 10” tart
 
For the Streusel-
 
1¼ cups + 2 tablespoons all-purpose flour
½ teaspoon ground cardamom
¼ teaspoon salt
½ cup dark brown sugar
1 stick (4 oz.) cold, unsalted butter cut into ½” pieces
 
In a medium bowl, whisk together the flour, cardamom, salt, and brown sugar. Using a bench scraper, cut in the butter pieces until the mixture resembles coarse crumbs. Cover and refrigerate.
 
For the Filling-
 
½ cup toasted walnuts, finely chopped
¼ cup + 2 tablespoons dark brown sugar
¾ teaspoon cinnamon
¼ teaspoon ground cardamom
pinch of salt
 
Combine all of the filling ingredients in a small bowl. Set aside while you prepare the pound cake batter.
 
For the Pound Cake batter-
 
¾ cup all-purpose flour
¾ cup white whole wheat flour
¾ teaspoon baking powder
¾ teaspoon baking soda
½ teaspoon salt
¼ teaspoon cinnamon
¼ teaspoon ground cardamom
3 oz. unsalted butter, room temperature
¾ cup sugar
1½ eggs (save the ½ for egg wash for a pie)
1 teaspoon vanilla
¾ cup low-fat plain yogurt
 
Fresh berries of your choice, for garnish
 
Preheat the oven to 325 degrees F. Butter and lightly flour a ten-inch tart pan with removable bottom. (Mine measures 10” across by 1½” deep.)
 
In a medium bowl, whisk together all of the dry ingredients. In the bowl of a standing mixer fitted with the paddle attachment, beat the butter and sugar on medium-high until pale and fluffy. Reduce speed to low. Add the egg and a half and the vanilla, mixing until combined. Scrape down the sides and bottom of the bowl.
Add the dry ingredients alternately with the yogurt. Do not over beat.
 
Place the tart pan on a parchment lined baking sheet. Place half of the pound cake batter in the tart pan, using an offset spatula to spread it evenly. Sprinkle the filling (not the streusel) over the first layer of batter. Top the filling with the remaining batter, spreading it evenly. Retrieve the streusel from the fridge. Sprinkle the streusel over the batter; it will come to the top of the pan. Bake the tart at 325 degrees F for 50-55 minutes, until the streusel is golden and the tart tests clean with a small knife. Cool the tart on a rack for 15 minutes (or more) before carefully removing the sides of the tart pan. Serve with fresh berries. Slice the cake using a serrated knife. Tightly wrap any leftovers in plastic wrap.