If you don't have a food processor you can use a stick blender or blender.
Drop fresh blueberries or raspberries into the mixture before pouring into the tin.
For a more chocolatey flavor, dust the top with cocoa powder if wished.
Replace vegetable oil with any neutral oil or coconut oil.
Replace honey with maple syrup if wished.
After pouring the mixture into the prepared baking pan, scatter over a cup of fresh or frozen raspberries or blueberries, pressing them lightly into the mixture with the back of a spoon. If using frozen berries this may increase the cook time by an extra 3-5 minutes.