Lay your bacon out onto a parchment lined sheet pan and place in your cold oven. Heat the oven to 400ºF and, once the oven is heated, set a timer for 8 minutes. Check the bacon for crispness. If golden and crisp, remove from the oven and transfer the bacon to a piece of paper towel to cool. Reserve the fat. If not, leave the bacon in the oven for a few more minutes, keeping an eye on it.
Lightly grease a 12-cup muffin tin with non-stick cooking spray and set aside.
In a large bowl, whisk together the cornmeal, flour, baking powder, baking soda, and salt and set aside. In a separate bowl, whisk together the pumpkin puree, buttermilk, brown sugar, maple syrup, and eggs. Measure out the bacon fat, if using, and add butter or oil if you don’t have ¼ cup. No matter the fat you’re using, add the fat into the wet ingredients and whisk to combine. Add the dry ingredients into the wet and stir just until combined. Set the batter aside for 10 to 15 minutes to allow the cornmeal to hydrate.
Chop the bacon and add to the hydrated batter along with the rosemary and stir to combine. Divide the batter into the prepared muffin tin and bake for 20 to 25 minutes or until risen, lightly golden, and a toothpick inserted into the centre of the muffins comes out clean.
