Preheat the oven to 400 degrees. Line two 5-by-9-inch loaf pans with foil. In a large bowl, whisk together the flour, salt and baking soda. Using your fingers, mix 2 tbsp. butter into the flour mixture until well incorporated (it should look like sand). Add the cheese; toss to coat. Add the buttermilk and stir until the dough just comes together. Divide between the pans; smooth the tops.
Cut a shallow cross all the way across the tops of the loaves. Thinly slice the remaining 1 tbsp. butter. Place the butter in the cuts in each loaf. Bake until the top is browned and a tester inserted in the center comes out clean, 25 to 30 minutes. Let cool in the pan at least 30 minutes before slicing.