Add 1/2 cup Greek yogurt, 2 tablespoons maple syrup, 3 tablespoons light olive oil, 1/3 cup milk, 1 teaspoon vanilla extract, and 2 eggs to a large bowl. Whisk until well blended and smooth. Add 1/2 cup oat flour, 1/4 cup gluten-free flour, 1/4 cup vanilla protein powder, 2 teaspoons baking powder, 2 teaspoons psyllium husk, and 1/4 teaspoon salt. Whisk until smooth with no lumps. Let the batter rest for 10 minutes. The batter will thicken as the oat flour and psyllium hydrate. Add more milk, 1 tablespoon at a time, until the batter pours easily but isn’t runny.