In a large mixing bowl, combine mashed potatoes, flour, baking powder, salt, and black pepper.
Stir in milk, olive oil (or melted butter), and eggs until the mixture is smooth and thick.
Fold in shredded cheddar, cooked bacon, and green onions or chives.
Heat a lightly oiled non-stick skillet over medium heat.
Scoop the batter into the skillet, flattening slightly to form cakes.
Cook for 3–4 minutes per side or until golden brown and crispy.
Remove and drain on paper towels. Serve hot, optionally topped with sour cream, fried eggs, or extra herbs.