Preheat the oven to 350 degrees F. Spray a baking sheet with nonstick cooking spray.
In a large bowl, combine the broccoli, cauliflower, eggs, breadcrumbs, Parmesan cheese, capers if using and a healthy pinch of salt and pepper. Mix everything together with your hands until everything sticks together. Using your hands, make patties out of the mixture, about 2 inches across, and place onto the prepared baking sheet.
Bake the cakes for 15 minutes, then flip and let cook for another 15 minutes.
You can use a food processor to grate the broccoli and cauliflower, or the large holes on a box grater.