Preheat your oven to 375°F (190°C) and lightly grease a small oven-safe baking dish with the coconut oil.
In a medium mixing bowl, whisk together the Greek yogurt, vanilla protein powder, egg, maple syrup, almond butter, cinnamon, vanilla extract, and sea salt until the batter is completely smooth and no protein powder clumps remain.
Gently fold in half of the fresh blueberries using a spatula to ensure they are evenly distributed throughout the custard base.
Pour the mixture into the prepared baking dish, using a spatula to smooth the top into an even layer.
Scatter the remaining blueberries across the top of the yogurt mixture, pressing them slightly into the surface so they stay in place.
Bake for 25 to 30 minutes until the edges are set and the center has a slight, firm jiggle when moved.
Remove from the oven and let the dish rest for 5 to 10 minutes to allow the custard to firm up and reach its ideal velvety consistency before serving.