Whisk in eggs, plain Greek yogurt, coconut sugar, and vanilla extract until no lumps of Greek yogurt remain and everything is well combined. Whisk in the baking powder, baking soda, and cinnamon.
Stir in the flour and protein powder and mix until just combined. Fold in about half the chocolate chips.
Pour the batter into your prepared loaf tin, and top with the remaining chocolate chips. Bake in the preheated oven for 55-60 minutes, covering halfway through with aluminum foil to prevent over-browning.
After baking, allow to cool, then slice and serve!