New England Cornbread

Butter (for the pan)
Flour (for the pan)
3 large eggs

1/2 cup butter, melted and cooled
1/2 cup oil
2 cups plain Greek yogurt
1/2 cup sugar
2 cups yellow cornmeal, preferably stoneground
1 cup all-purpose flour
1 1/2 tsp baking powder
1/2 tsp baking soda
1/2 tsp salt

Heat the oven to 375F, butter a 9x13 baking pan. Line the bottom with parchment and butter the paper. In a bowl large enough to hold all the ingredients, stir together oil, butter and yogurt until smooth, then stir in the eggs. Add in the sugar followed by the cornmeal, flour, baking powder, baking soda, and salt. Keep stirring until no pockets of dry ingredients show. Pour the batter into the pan and smooth the top. Bake the cornbread for 35 minutes, or until it is uniformly golden brown on top and firm in the middle (insert toothpick in center to see if it comes out dry). Set on a rack to cool for 10 minutes. Slice the cornbread into 18 squares