Preheat your oven to 350°F. Spray a 9- by 5-inch loaf pan with nonstick spray, line the bottom and sides with parchment paper and spray again. Set aside.
In a small mixing bowl, combine the brown sugar and 1 teaspoon cinnamon. Stir to combine. Set aside.
In a medium mixing bowl, whisk together the flour, baking powder, salt and remaining 1 teaspoon cinnamon. Set aside.
In a bowl of an electric mixer fitted with a paddle attachment, cream the butter, coconut sugar and granulated sugar for about 2-3 minutes on medium-high. Scrape down the sides of the bowl and mix again for another 2 minutes.
With the mixer on medium speed, add the vanilla and eggs, scraping down the sides and bottom of the bowl between each addition.
With the mixer on low speed, alternately add the flour mixture and the Greek yogurt, starting and ending with the flour mixture.
Pour half of the batter into your loaf pan. Sprinkle 3/4 of the brown sugar-cinnamon mixture over the batter. Gently spread the remaining batter over the brown sugar-cinnamon mixture and sprinkle with the remaining brown sugar-cinnamon.
Bake for 40-45 minutes, or until a toothpick inserted into the center of the loaf comes out with a few moist crumbs on it.
Let cool in the pan for about 15 minutes before inverting to cool on a wire rack. Serve warm or at room temperature.