To prepare a vegetarian breakfast casserole with hash browns recipe, you'll need: 1 1/2 cups sourdough bread, 1 cup shredded cheddar cheese, 2 tablespoons olive oil, and 1 teaspoon kosher salt. Preheat the oven to 350?F (180?C) and grease 2 9-inch square baking pans. Mix the flour, baking powder, salt, pepper and thyme together. Add the milk and stir to combine. Pour the dry ingredients into the wet ingredients and mix until the ingredients are evenly coated. Bake the casserole for 35 to 40 minutes or until browned and bubbly. Serve warm.