Heat the oven to 375°F. Grease all 12 wells and the surrounding surface of a standard metal muffin pan.
Rinse spinach under running water, spin and blot thoroughly dry, then chop into pieces no larger than 1/2 inch.
Whisk flour, baking powder, oregano, garlic powder, salt and pepper in a large bowl for 20 seconds.
Blend cottage cheese, eggs, milk and olive oil for 20 to 30 seconds until smooth and uniform.
Fold wet mixture into dry just until only a few flour streaks remain.
Fold in spinach, scallions and 2/3 cup cheddar. Rest 5 minutes; add 1 tablespoon milk if sharply stiff or 1 tablespoon flour if the batter flows flat.
Divide among 12 wells, filling about three-quarters full. Top with the reserved cheddar.
Bake 21 to 26 minutes until tops are light golden, centers spring back and a tester has moist crumbs without liquid batter. The center must reach at least 160°F; a set bread crumb is usually 195 to 200°F.
Cool in the pan 8 minutes, loosen the edges and transfer to a wire rack for at least 20 minutes.
