Preheat the oven to 375°F. Lightly coat 24 larger mini muffin cups or 36 smaller mini muffin cups with cooking spray (used a shaped tin for an extra pop!)
Whisk the eggs, milk, and butter in a large bowl. Add the corn muffin mix and stir until blended but still lumpy. Divide among the muffins cups, filling each three-quarters full.
Bake until golden and a toothpick inserted in the center of one comes out clean 12 to 15 minutes. Remove from the tins and cool completely on a wire rack.
While the muffins bake and cool, mix the cheese, mayonnaise, pimentos, and cayenne in a bowl.
Trim the tops of the muffins or cut a cavity in each. Divide the pimento cheese among the muffins and garnish with a pimento pepper.