Preheat the oven to 350°F (175°C). Lightly grease a 9x13-inch baking dish with non-stick spray or butter. Set aside.

Prepare the cornbread batter according to the package directions in a large mixing bowl. Once the batter is fully mixed, gently stir in the vanilla extract and orange zest until incorporated.

Assemble the first layer by spreading half of the prepared batter evenly into the bottom of the greased baking dish using a spatula.

Add the berries by evenly distributing the raspberries and blueberries across the top of the first layer of batter.

Add the second layer by carefully spooning and spreading the remaining batter over the berries. It is acceptable if some of the fruit remains visible.

Create the topping by combining the brown sugar and ground cinnamon in a small bowl. Sprinkle the mixture evenly over the top layer of batter.

Bake the cake in the preheated oven for 55 to 65 minutes, or until the top is golden brown and a toothpick inserted into the center comes out clean or with only a few moist crumbs.

Cool before serving. Allow the coffee cake to cool on a wire rack for 15 to 20 minutes before slicing. Serve warm or at room temperature. Optional garnishes include whipped cream and additional fresh berries.