Preheat oven to 425°F (220°C) with a 9" cast-iron skillet inside.

In a small bowl, combine 1 cup whole milk with 1 cup cornmeal. Soak for 10 minutes.

Sift together 1 cup all-purpose flour, 4 teaspoons baking powder, and 3/4 teaspoon table salt in a medium bowl. Add soaked cornmeal mixture, 2 lightly beaten large eggs, 1/4 cup melted unsalted butter, and 2 tablespoons vegetable oil. Mix until smooth, about 1 minute.

Carefully remove preheated skillet, add a bit of oil to coat, discard excess. Pour batter into skillet and return to oven.

Bake until a toothpick inserted into the center comes out clean, about 18–23 minutes.

Rest cornbread in skillet for 5 minutes. Cut into wedges and serve warm.