If you have a kitchen scale, I encourage you to use the weight measurements provided for the best accuracy. If you don't have a scale, be sure to measure the flour with the spoon and level method to avoid adding too much flour.
Preheat oven to 340F (regular bake setting/not convection or fan-assisted). Prepare an 8x8-inch metal baking pan by spraying it with cooking spray and lining the bottom and two sides with parchment paper, allowing the parchment to extend beyond the sides to use as handles to remove the cake after baking. (If using a glass pan, reduce the oven temperature to 315F.)
Prepare the fruit and sprinkle with the flour. Stir gently to coat. Set aside.
In the bowl of a stand mixer fitted with the paddle attachment or a large bowl with an electric beater, cream together the butter and sugar at medium speed until light and fluffy, about 2 minutes. Beat in the eggs one at a time, scraping down the bowl as necessary. Mix in the vanilla.
In a medium bowl, whisk together the flour, baking powder and salt. Add to the cake batter alternately with the yogurt, mixing just until combined. Remove the bowl from the mixer.
Remove 1/3-1/2 cup of the fruit and set aside. Add the remaining fruit to the cake batter and use a spatula to gently incorporate it.
Spread the batter into the prepared pan and spread it out evenly. Scatter the reserved fruit over the top of the cake, then sprinkle the top of the cake with the granulated sugar.
If using frozen fruit, the cake may need a few minutes more baking time.
Bake the cake in the preheated oven for 40-45 minutes, checking after about 30 minutes of baking and covering the top loosely with a sheet of aluminum foil for the last part of baking if it is browning too quickly. Test with a cake tester or toothpick. The tester should come out dry with maybe a couple of crumbs.
Remove the cake from the oven and allow it to cool in the pan for 30-45 minutes before removing the cake from the pan and slicing.
Notes
Note 1: You can use just one type of berry or a mixture of any berries, fresh or frozen.Tips!Store this cake loosely covered at room temperature for 2-3 days, though it is best enjoyed within 24 hours of baking. This cake will freeze well for up to 3 months.Be sure to read the notes above this Recipe Card for more tips on making this recipe, substitution suggestions and step-by-step photos that you might find helpful.