Preheat oven to 350°F. Position a rack in the center and lightly butter an 8-inch springform pan and dust with flour.​

In a medium bowl, vigorously whisk together 1 cup of flour with the baking powder, salt, and cinnamon. Set aside. ​

Using an electric mixer, beat the butter on medium high speed for 2 minutes. Add the sugar and beat until light and fluffy, 1 to 2 minutes more. Beat in the vanilla extract. Add the eggs one at a time and beat until well blended, scraping down the sides of the bowl as needed. Beat in the lemon zest, if using. Reduce the speed pf the mixer to low and slowly add the flour mixture, beating until smooth. The batter will be thick. ​

Put the batter in the prepared pan, smoothing the top with a spatula. ​

Combine the berries with the remaining teaspoon of flour and the lemon juice in a bowl. Spoon the berry mixture over the batter. ​

Bake for 45 to 55 minutes at 350°F, or until a tester inserted into the center comes out clean. Remove from the oven and let cake cool in pan for 10 minutes.​

Transfer cake to a platter, berry side up. Dust cake with powdered sugar and serve!​