Preheat oven to 400°F and place rack on the center shelf.
Melt butter over medium heat in a cast iron skillet.
Whisk together milk, buttermilk, eggs, and creamed corn in a small bowl. Set aside.
Whisk together cornmeal, flour, thyme, baking powder, and salt in a large bowl. Stir in egg mixture.
Pour batter into skillet and smooth out the top. Place in oven and bake until golden brown, about 25 minutes, or until a toothpick comes out clean.