Preheat your oven to 350°F and lightly grease a small ceramic ramekin with a touch of coconut oil.
In a medium mixing bowl, whisk together the chocolate protein powder, oat flour, cacao powder, baking powder, and sea salt until well combined.
Add the liquid egg whites, maple syrup, and melted coconut oil to the dry ingredients, stirring until the batter is completely smooth.
Pour the batter into the prepared ramekin and bake for 12 to 14 minutes, ensuring the edges are firm while the center remains soft to the touch.
While the cake bakes, combine the raspberries, lemon juice, and water in a small saucepan over medium heat.
Simmer the raspberry mixture for 5 minutes, mashing the berries with a fork until the sauce thickens slightly.
Press the raspberry sauce through a fine-mesh sieve into a small bowl to remove the seeds and create a smooth coulis.
Remove the cake from the oven, let it sit for 2 minutes, then carefully invert it onto a plate and top with the warm raspberry coulis.