Mix the wet ingredients. In a medium bowl, whisk together the Greek yogurt, eggs, vanilla extract, and honey or maple syrup if you are using it.
Keep mixing until the texture looks smooth and even.
Add the dry ingredients. Stir in the oats, flour, protein powder, baking powder, cinnamon, and salt. Mix gently until everything combines. The batter should be thick but still spoonable.
Adjust the consistency. Add 1 tablespoon of milk at a time if the batter feels too stiff.
Stop once it drops easily from a spoon but still holds some shape.
Fold in the berries. Gently stir in about half of the berries. Save the rest for topping the pancakes after cooking.
Heat the pan. Warm a nonstick skillet or griddle over medium heat. Add a small amount of butter or oil and spread it around the surface.
Cook the pancakes. Scoop about 1/4 cup of batter for each pancake onto the pan.
Cook for 2 to 3 minutes, until bubbles appear and the edges start to look set.
Flip carefully. Turn each pancake and cook for another 1 to 2 minutes, until golden brown and cooked through. Lower the heat if the pancakes brown too quickly.
Serve warm. Stack the pancakes and top with the remaining berries. Add extra Greek yogurt, a drizzle of honey, or a sprinkle of nuts if you like.