Preheat the oven or toaster oven to 350°F. Grease a standard loaf pan and set aside.
In a large mixing bowl, whisk together the flour, baking powder, baking soda, salt, garlic powder, and black pepper.
Add the finely diced garden peppers and 1½ cups shredded cheddar cheese to the dry ingredients. Toss until the peppers and cheese are lightly coated with flour. This helps keep them suspended throughout the bread instead of sinking toward the bottom.
In a separate bowl, whisk together the sourdough starter, eggs, milk, melted butter, and honey or sugar, if using.
Pour the wet ingredients into the dry ingredients. Gently fold everything together just until the flour is moistened. Do not beat or overmix the batter.
The batter should be thick, heavy, and scoopable, similar to a thick muffin batter. If it seems unusually dry, stir in additional milk 1 tablespoon at a time.
Spoon the batter into the prepared loaf pan and spread it evenly. Sprinkle additional shredded cheddar over the top, if desired.
Bake at 350°F for 40–50 minutes, beginning to check the loaf at about 35 minutes. The top should be golden brown and the center should be fully baked.
If the top becomes nicely browned before the center is finished baking, loosely tent the loaf with aluminum foil and continue baking until done.
Remove the bread from the oven and allow it to rest for 15 minutes before slicing. This resting time helps the cheesy interior set so you get clean, sturdy slices.