Preheat oven to 400 degrees F (200 degrees C). Set butter in a 6x10-inch casserole dish; place dish in the preheating oven until butter is melted.
Mix cottage cheese, Jack cheese, green chiles, eggs, flour, baking powder, and salt in a large bowl using an electric hand mixer.
Pour mixture into the melted butter in the casserole dish.
Bake in the preheated oven for 15 minutes. Reduce heat to 350 degrees F (175 degrees C); bake until middle of casserole is set, about 50 more minutes. Allow to stand for 10 minutes before serving.
