Preheat the oven to 350°F and grease or line a 6x8-inch baking dish.
Add the egg and whisk. Add the Greek yogurt, maple syrup, coconut oil, and vanilla to the baking dish and whisk with a fork until smooth.
Add the chia seeds and stir well. Add the flour, cinnamon, baking powder, baking soda, and salt. Stir with a silicone spatula just until combined, then spread evenly.
If doing the cinnamon swirl, in a small bowl, stir together the melted coconut oil, brown sugar and cinnamon.
Drizzle or dollop the swirl over the batter and gently swirl with a butter knife.
Bake for 30 minutes, until brown on top and cooked through the centre. Cool slightly before serving. Drizzle or pipe yogurt "icing" on top!