Preheat oven to 375° F.
Line the muffin pan with 12 standard muffin cup paper liners (if you have 2 muffin pans, then you can bake all 15 at the same time). I used a 6-cup muffin pan and saved the batter to bake more the next day.
Place a small skillet over medium-high heat and add 2 tablespoons unsalted butter and 2 tablespoons EVOO.
When the oil and butter are hot, add the thinly sliced onions. Sauté until the onions are slightly brown and soft.
Add kosher salt and freshly cracked black peppercorns to taste
Add the chopped sage and minced garlic, and sauté for 2-3 minutes, until the garlic is fragrant. Set aside and allow the onion, garlic, and sage mixture to cool completely.
Into a large mixing bowl, add 2 boxes of Krusteaz Horny Cornbread mix, 2/3 cup extra virgin olive oil, 1 cup whole milk, 2 eggs, and 2 tbsp dried Italian Seasoning blend, and mix well.
Fold in the sautéed onions, garlic, and sage mixture.
Fill the paper muffin liners 3/4 full with the cornbread batter and top each one with a fresh sage leaf.
Bake the muffins for 20-25 minutes. Use a toothpick to check for doneness. The muffins should be golden, set in the center, and pass the toothpick test. If not, bake for another 5-10 minutes.
When the muffins are out of the oven, brush each one with melted butter.
Serve.