1Heat the oven to 400°F. Coat a 12-cup muffin pan with cooking spray, or use muffin cups liners.
2In a large bowl, whisk together the flour, baking powder, baking soda, pepper, salt, and cayenne pepper.
In a medium bowl, whisk together the eggs, buttermilk, oil, and butter. Stir in the scallions, ham, cheese, and bell pepper.
3Add the wet ingredients to the dry and use a rubber spatula to mix until just moistened. Scoop the batter into the prepared pan (heaping 1/4 cup each for unlined 12-cup muffin pan, scant 1/4 cup each for lined 12-cup muffin pan.
4Bake the muffins until the tops are browned (at high altitude, about 28 minutes for unlined 12-cup muffin pan, 22 minutes for lined.
Let the muffins cool in the pan for 15 minutes then loosen the edges with a knife (if necessary) and transfer the muffins to a cooling rack. Serve warm.