Heat oven to 350 degrees F. Grease 9" X
13" cake pan with the butter.
Combine the flour, granulated sugar,
baking powder, cinnamon, baking soda, and salt in a medium
bowl. In a separate bowl, whisk together the buttermilk,
eggs, oil, and vanilla. Add the wet ingredients to the dry
ingredients and whisk to combine.
Pour the batter in the pan, top with
diced peaches and raspberries. Sprinkle top with a little
granulated sugar and cinnamon. Bake at 350 degrees F, until
a toothpick inserted in the center of the cake comes out
clean, 35-45 minutes. Cool in the pan for 5 minutes. Run a
knife around the outside edge of the cake to loosen. Cut and
serve while warm.