From https://www.southernliving.com/syndication/plum-berry-cornmeal-sheet-cake
3/4 cup (6 oz.) salted butter, softened
1 1/2 cups granulated sugar
4 large eggs
1 1/2 cups (about 6 3/8 oz.) all-purpose flour
1 cup fine yellow cornmeal
2 teaspoons baking powder
1 teaspoon kosher salt
3/4 cup sour cream
1 tablespoon orange zest plus 1/2 cup fresh juice (about 2 oranges)
2 teaspoons vanilla extract
2 1/2 cups mixed fresh berries
2 red plums, sliced
1. Oven 350
Line 13x9 greased pan w parchment paper
Beat butter, sugar until light and fluffy; add eggs, individually, beating well.
2. Whisk together flour, cornmeal, baking powder, salt in a medium bowl; which sour cream, orange zest and juice, and vanilla in a small bowl. Add flour to butter, alternating with sour cream mix, beating until just blended after each addition. Spread into prepared pan.
3. Scatter berries and sliced plums (or peaches) over the batter.
4. Bake until a knife comes out clean, 55 minutes to 1 hour and 5 minutes. Cool on a rack 20 minutes. Cut into squares. Serve at any temp.