Perfect for a Sunday brunch.
Preheat the oven to 375°F. Grease a 9-inch square baking pan and line with parchment paper so the parchment comes above the rim of the pan on 2 opposite sides.
Whisk together in a medium bowl:
Beat in a large bowl or stand mixer fitted with the paddle attachment until light and fluffy:
Beat in:
Beat in:
Beat in the flour mixture in 2 additions, alternating with:
Stir or mix until smooth. Spread the batter in the prepared pan. If desired, toss together and sprinkle over the batter:
Then sprinkle with:
Bake until a toothpick inserted in the center of the cake comes out clean or with moist crumbs attached, about 25 minutes if covered with streusel alone, 25 to 30 minutes if covered with fruit and streusel. Let cool in the pan on a rack.