Preheat oven to 450 degrees.
In a medium bowl, combine cornmeal, flour, baking powder, salt, and cayenne. In a small bowl, combine milk, garlic, and egg.
Add milk-egg mixture to dry ingredients and stir just to combine. Heat a 10-inch cast-iron skillet over medium heat and add 1 tablespoon vegetable oil. Add 1 tablespoon vegetable oil to cornmeal batter. Whisk to combine, then quickly pour batter into hot skillet.
Return skillet to oven and bake for 20 minutes, until edges are browned and cornbread has begun to pull away from sides of pan and middle is set. Turn out cornbread onto a cutting board and top with butter. Cut into wedges and serve immediately.