Add the oat flour, vanilla protein powder, eggs, almond milk, vanilla, cinnamon, and salt to a blender. Blend until smooth, about 15 to 20 seconds. The batter should be thin enough to flow easily when the blender is tilted.

Let the batter rest for 5 minutes. Oat flour and protein powder will absorb some liquid during this time. If the batter becomes noticeably thick, whisk in 1 tablespoon (15 ml) almond milk at a time until it returns to a thin, pourable consistency.

In a small bowl, stir the softened butter, brown sugar, and cinnamon together until smooth and spreadable. Set aside.

Whisk the Greek yogurt, powdered sugar, vanilla, and almond milk in another small bowl until smooth. The topping should be creamy and thin enough to drizzle. Add a few drops of almond milk if necessary.

Place a 10-inch nonstick skillet over medium-low to medium heat. Lightly brush it with a little oil. The surface should be hot enough for the batter to begin setting immediately but not so hot that it browns before spreading.

Stir the batter briefly: Pour about 1/4 cup (60 ml) into the center of the skillet and immediately tilt the pan in a circular motion to spread the batter into a thin layer.

Cook for about 45 to 60 seconds, until the surface looks mostly dry and the edges begin to lift. The underside should have light golden spots.

Carefully slide a flexible spatula underneath the crepe and flip it. Cook for another 15 to 20 seconds, just until the second side is set. Avoid overcooking because protein-rich crepes can become dry or rubbery.

Transfer the cooked crepe to a plate and repeat with the remaining batter. Lightly oil the skillet between crepes only when needed.

Spread a thin layer of the cinnamon filling over each warm crepe. Do not use too much filling, as a heavy layer can make the stack difficult to fold and eat.

Stack the filled crepes and cut the stack into wedges, or roll each filled crepe into a cylinder. For a more cinnamon-roll-like presentation, stack several filled crepes and slice into portions.

Drizzle the creamy vanilla topping over the warm crepes. Serve immediately while the crepes are tender and the cinnamon filling is soft.