Preheat the oven to 375°F (190°C). Lightly coat a baking tray with cooking spray so the falafel don’t stick and crisp up nicely.
Place the chickpeas, onion, garlic, parsley, olive oil, lemon juice, cumin, coriander, salt, and cayenne into a food processor. Pulse in short bursts until the mixture comes together but still has a slightly coarse texture. It should not turn into a smooth paste, since a bit of texture helps the falafel hold shape and taste better.
Add the baking soda and oat flour, then mix again until everything is evenly combined. The mixture should feel thick enough to shape and hold together when pressed.
Scoop small portions of the mixture and shape them into patties or small balls. Arrange them on the prepared baking tray, leaving a little space between each piece. You should get around 15 falafel.
Bake for 10–12 minutes, then carefully flip each piece. Bake again for another 10–12 minutes until they are golden on the outside and firm in the center.