german sunken plum cake

german sunken plum cake
adapted from luisa weiss's sunken lemon-cherry cake in classic german baking 

130 g. (9 tbsp. + 1 tsp.) butter, at room temperature
180 g. (1 c. minus 1.5 tbsp.) sugar
3 eggs
grated peel of one lemon
180 g. wheat flour
     or gluten-free:
     70 g. millet flour
     55 g. sweet rice flour
     55 g. potato starch
     1 tsp. xanthan gum
1/2 tsp. baking powder
1/4 tsp. salt
300 — 400 g. (about 1.5 cups) quartered plums, pitted sour cherries, other stone fruit
icing sugar to dust (optional)

Turn the oven on to 350 degrees Fahrenheit. Use parchment paper to line the bottom of a 9-inch/23 cm springform pan.

Beat the butter and sugar together until fluffy. Beat in the eggs one at a time. Mix in the grated lemon peel.

In another bowl, stir the flour(s), baking powder and salt together. Stir into the butter mixture until just combined. Make sure you've scraped the sides down to mix everything. If you are putting fruit in the batter (you may just put it on top), fold it in now.

Put the batter into your prepared pan and smooth the top. If you're putting fruit on top, do it now.

Bake for 50 — 60 minutes until it's golden brown and starting to pull away from the side of the pan.

Cool on a rack for 20 minutes before taking off the springform ring. You may dust with icing sugar before serving.