Preheat the oven to 375°F and spray a 12 cup muffin tin with nonstick spray.
Cook the bacon in a skillet over medium heat until very crispy, about 8 to 10 minutes. Drain on paper towels and crumble once cooled.
In a large bowl, whisk together the flour, sugar, baking powder, baking soda, salt, and cinnamon until evenly combined.
In a separate bowl, whisk together the buttermilk, eggs, maple syrup, butter, and vanilla until smooth.
Pour the wet ingredients into the dry ingredients and gently stir until just combined. Do not overmix.
Gently fold most of the bacon into the batter, saving a little for topping.
Divide the batter evenly among the muffin cups, filling each about two thirds full.
Sprinkle remaining bacon on top and bake for 15 to 18 minutes until golden and a toothpick comes out clean.
Let muffins cool for 5 minutes, then remove and serve warm with extra maple syrup if desired.