Preheat the oven to 350 degrees Fahrenheit. Grease an 8½ x 4½- inch loaf pan and line with parchment paper. Set aside.
In a medium bowl, add 2 cups all-purpose flour, 1 teaspoon baking powder, ½ teaspoon baking soda, 1 teaspoon salt, and 1 teaspoon cinnamon. Whisk to combine.
In a large bowl, add ½ cup vegetable oil, 1 cup sugar, 2 eggs, 1 cup buttermilk, and 1 tablespoon vanilla. Whisk to combine. Add the dry ingredients to the wet ingredients and stir together until just combined.
Pour half of the batter into the prepared loaf pan. Stir together 2 tablespoons granulated sugar and 1 teaspoon cinnamon, and sprinkle over the batter. Add the remaining batter over the cinnamon sugar mixture.
Bake for 50-55 minutes, or until a toothpick inserted into the center comes out clean. Let cool for 10 minutes, then remove from the pan onto a wire rack to cool.
In a small bowl, whisk together 1 cup powdered sugar, ½ teaspoon cinnamon, 2-3 tablespoons whole milk, and 1 teaspoon vanilla. Pour the glaze over the loaf and allow to set before slicing and serving.
Notes
Storage & Make Ahead Tips
Room Temp: Store leftovers in an airtight container at room temperature for up to 4 days.
Freezer: Cool completely, then wrap tightly in plastic wrap and place in a freezer bag. Freeze whole or sliced for up to 3 months.
Make Ahead: Assemble the batter in the loaf pan, cover, and refrigerate for up to 24 hours before baking. Add about 5 minutes to the bake time.