Preheat oven to 350°F (175°C) and lightly grease a standard loaf pan or 6-inch bundt pan.

In a large mixing bowl, whisk together the self-rising flour and the vanilla protein powder.

Add the non-fat Greek yogurt to the dry ingredients and stir until a shaggy dough forms.

Transfer dough to a lightly floured surface and knead for 1-2 minutes until smooth and elastic.

In a separate small bowl, combine the granulated erythritol and ground cinnamon.

Pinch off pieces of dough and roll into approximately 30 small, bite-sized balls.

Roll each ball individually in the cinnamon-sweetener mixture until thoroughly coated.

Layer the coated dough balls into the prepared pan.

Whisk the vanilla extract into the melted butter and drizzle evenly over the top of the dough balls.

Bake for 25 minutes or until the bread has risen and the surface is golden brown.

Let rest in the pan for 5 minutes before inverting onto a plate to serve.