Preheat the oven to 350°F (175°C). Grease a 9×5-inch loaf pan or line it with parchment paper.
In a large bowl, whisk together 2½ cups (300g) all-purpose flour, 2 teaspoons baking powder, ½ teaspoon baking soda, 1 teaspoon salt, ½ teaspoon garlic powder (if using), ½ teaspoon black pepper, and 1 teaspoon Italian seasoning (if using) until well combined.
In a separate bowl, whisk together 2 large eggs, 1 cup (240ml) buttermilk, ⅓ cup (80ml) olive oil, and 2 tablespoons melted butter until smooth.
Pour the wet ingredients into the dry ingredients and stir gently until almost combined. Fold in 1 cup (110g) shredded sharp cheddar cheese, ½ cup (50g) grated Parmesan cheese, and ¾ cup sliced olives. Mix just until no dry flour remains, being careful not to overmix.
Pour the batter into the prepared loaf pan and spread it into an even layer. If you'd like, sprinkle a little extra cheese on top. Bake for 50–60 minutes, or until a toothpick inserted into the center comes out clean.
Let the bread cool in the pan for 10–15 minutes, then transfer it to a wire rack to cool before slicing and serving.
