Preheat the oven to 350 degrees F and line muffin tins with paper cups.
In a bowl, whisk together the flour, cornmeal, sugar, baking powder, kosher salt and baking soda until fully incorporated.
In a second bowl, whisk together the eggs, sour cream, milk, olive oil, maple syrup, vanilla and zest (if using) until fully incorporated.
Add the dry ingredients into the wet in two stages, whisking until fully combined. stop whisking so you don't overmix.
Fill the paper lined cups with batter for about 24 smaller muffins or 18 bigger muffins.
Bake for 35 to 45 minutes.
While the muffins bake, vigorously whisk the butter with the maple syrup until whipped. serve with the muffins (even better when they’re warm!)
