Preheat your oven to 350°F and lightly grease a standard-sized ceramic ramekin with a small amount of coconut oil.
In a medium mixing bowl, whisk together the egg whites, Greek yogurt, and melted coconut oil until the mixture is smooth and well combined.
Sift in the chocolate protein powder, cocoa powder, almond flour, baking powder, and sea salt, then gently fold the dry ingredients into the wet until a thick batter forms.
Pour the batter into the prepared ramekin, ensuring the top is leveled with a spoon.
Bake for 12 to 14 minutes; the edges should be firm and set while the very center remains slightly soft to the touch to ensure a molten core.
While the cake bakes, place the raspberries, maple syrup, and water in a small saucepan over medium heat.
Simmer the raspberry mixture for 5 minutes, mashing the berries with a fork until they break down into a thick sauce.
Remove the cake from the oven and let it cool for 2 minutes before carefully running a knife around the edge and inverting it onto a plate.
Spoon the warm raspberry coulis over the top of the cake and serve immediately while the center is still liquid.