Combine the flour, half of the Natvia, the baking powder, ½ tsp cinnamon, salt and stir to combine. In a separate bowl combine the remaining Natvia, chia and cinnamon.
Combine the egg, buttermilk, vegetable oil and vanilla and pour over the flour mixture, stir until combined. Pour half the batter into a greased loaf tin
Stir the melted butter through the Natvia and cinnamon mixture. Drizzle over the batter and use a skewer or knife to swirl. Add the remaining batter. Tap on the bench firmly to remove any air bubbles. Place in the oven for 5 minutes, then lower the temperature to 170C to bake for 40-45 minutes. Remove form the oven and stand in the tin for 10 minutes before removing to a wire rack to cool completely. Slice and serve.