To make the Orange Butter: in a small bowl using the back of a spoon, cream the butter and zest until fluffy and well combined; store, covered, in the refrigerator for up to 1 week; bring to room temperature before serving.
To make the bread: preheat the oven to 375°; grease a 9-inch round springform or square cake pan.
In a bowl, combine the flour, cornmeal, baking powder, baking soda, salt, and spices.
In a small bowl, mix the eggs, sweet potatoes, corn oil, maple syrup, and buttermilk with a whisk.
Add the wet mixture to the dry ingredients; stir just until all ingredients are moistened yet thoroughly blended.
Take care not to overmix.
Pour the batter into the prepared pan; bake in the center of the oven about 20-25 minutes, until the cornbread is golden around the edges and a cake tester comes out clean.
Let stand for 15 minutes before cutting into thick wedges.
Serve with Orange Butter.