Plum snack cake with Pecan Topping

We got in the habit of making this cake to use up fruit that was on the verge of being overripe. The plums give it a sweet and sour counterpoint and its a great little cake for afternoon snacks or bring it to a pot luck. 

​Plum Snackcake with Pecan Topping
 
Topping:
¼ cup packed light brown sugar
¼ cup all-purpose flour
2 tablespoons unsalted butter (¼ stick), plus more for
coating the pan
½ teaspoon ground cinnamon
Pinch fine salt
½ cup finely chopped pecans
 
Cake:                      
1 ¼ cups all-purpose flour
1 teaspoon baking powder
¼ teaspoon salt
1/3 cup whole milk
1 teaspoon vanilla extract
¾ cup sugar
6 tablespoons unsalted butter at room temperature
2 eggs, at room temperature
5 medium plums, pitted and cut into ¾ -inch pieces
 
Heat the oven to 350°F and arrange a rack in the middle.   Coat an 8-by-8-inch baking dish with butter and set aside.

To make topping, in a medium bowl use your fingertips and work the brown sugar, flour, butter, cinnamon, and salt until the ingredients come together. Stir in the pecans, cover, and refrigerate until ready to use.
 
To make cake, whisk the flour, baking powder, and salt together in a medium bowl and set aside. Whisk together the milk and vanilla extract in a small bowl and set aside.  Combine the sugar and butter in the bowl of a stand mixer fitted with a paddle attachment and beat on medium speed until light in color and fluffy, about 3 minutes. You can also use a hand held mixer.  Add the eggs 1 at a time, letting the first completely incorporate before adding the second. Add a third of the flour mixture and mix on low until just combined; scrape down the sides of the bowl. Pour in half of the milk mixture and mix on low until just incorporated. Repeat, alternating dry and wet ingredients and ending with the dry ingredients, until completely incorporated.

Remove the bowl from the mixer, fold the plums and turn the batter into the prepared baking dish. Sprinkle the reserved topping evenly over the top and bake until a tester inserted into the center comes out clean and the top is golden brown, about 45 to 50 minutes. Remove from the oven and let cool at least 20 minutes before serving.