For the frosting: Cook the bacon, over medium heat in a small skillet, until crisp. Transfer to a plate lined with paper towels to drain and cool, then chop and set aside. Combine the remaining ingredients, except the scallions, in a medium bowl and mix well. Refrigerate for 2 hours.;
For the batter: Preheat oven to 375 degrees F.
In a large bowl add the flour, cornmeal, sugar, eggs, buttermilk and 3 tablespoons melted butter. Mix well to combine.
Saute onions and jalapenos using 1/4 tablespoon butter, about 2 minutes. Add salt, pepper and chiles. Remove from heat, cool slightly and add to the batter.
Spray 2 (12 capacity) muffin pans with nonstick spray. Fill the pans 3/4 full with the batter. Bake for 12 to 15 minutes until golden. Let cool and frost with pimento cheese mixture. Garnish with chopped bacon and chopped scallions.
Mix all ingredients together and store in an airtight container for up to 3 months.