To make the cupcakes: Preheat an oven to 350 degrees F. Spray nonstick minimuffin tins with cooking spray or lightly oil them. (The muffin tin cups should be 3/4 to 2 inches in diameter.) Set aside.

In a large sauté pan or skillet over medium heat, melt the butter and sauté the onion, celery, and bell pepper for about 3 to 4 minutes, until just starting to get tender. Let cool.

Meanwhile, in a small bowl, whisk together the cornmeal, flour, sugar, baking powder, and Old Bay. In a large bowl, whisk together the egg, milk, and sour cream.

When the sweated vegetables are cool, add the cornmeal mixture to the egg mixture, and mix lightly. Stir in the vegetables and all the melted butter from the pan, but do not overmix. Fold in the crabmeat just until evenly distributed.

Spoon a heaping tablespoon of batter into each muffin cup. You should fill 20 cups. Bake the cupcakes for about 12 to 14 minutes, or until a toothpick inserted in cupcake centers comes out clean. Rotate the pans after the first 7 to 8 minutes of baking.

Let the cupcakes cool in the pan for about 20 minutes, then carefully remove them from the pan and let cool briefly on a wire rack before frosting. The cupcakes can be made up to 1 day in advance, covered, and refrigerated before frosting. Refrigeration is imperative as the crab perishes swiftly if left at room temperature for an extended period of time. Bring to room temperature or warm for a minute or so in the oven before frosting.

To make the frosting: In a small bowl, mash the cream cheese with a fork, then whisk in the milk and lemon juice until smooth and creamy. Top each cupcake with about 1 teaspoon of frosting, then sprinkle with about 1/4 teaspoon of chives for garnish.