To make the filling, toss all the filling ingredients together in a bowl.
Spoon into an 8-inch square baking pan.
To make the topping, pulse the flour, baking powder, baking soda, salt, and cinnamon in a food processor with the cold butter until it resembles coarse meal.
Place the mixture in a bowl.
In a separate bowl, whisk together the lemon zest, agave nectar, and buttermilk.
Make a well in the center of the flour mixture and slowly pour the buttermilk mixture into the well.
Use a fork to gently stir the ingredients together to form a dough.
Turn the dough out onto a lightly floured work surface and pat into an 8-inch square.
Drape the dough carefully over the fruit, cobbling it by pinching it all over the top.
Take care not to tear it.
If you do make a hole, just press the dough together with your wet fingers.
Prick the dough all over with a fork and bake for 35 to 40 minutes, until golden.
Let cool in the pan for 15 to 20 minutes to set before serving.