In a food processor, combine flour, sugar, baking powder, salt, cinnamon, and 1 cup oats and pulse a few times to coarsely grind oats. In a large bowl, whisk together milk, eggs, and oil. Add dry ingredients and 1 cup oats and whisk just until moistened.
Heat a large skillet (nonstick or cast-iron) or griddle over medium. Lightly oil skillet. Using 2 to 3 tablespoons for each pancake, drop batter in skillet and cook until a few bubbles have burst, 1 to 2 minutes. Flip pancakes and cook until browned on undersides, 1 to 2 minutes more. Repeat with more oil and batter.